united-states
When is a single wet ink original necessary?
First of all, signing a will or medical power of attorney or a declaration as to medical or surgical treatment, or any other document that must be witnessed, in multiple counterparts, is inappropriate. This undermines the purpose of the witnesses and notarization, and the law governing the revocation of a will implicitly demands a single original document. In a worst case scenario, a will executed this way may be invalid or may be held to be not self-proving.
A will is like a dollar bill, a copy is not is good as the original, and it needs to be a single document. (So are original promissory notes, checks, negotiable warehouse receipts, negotiable stock certificates, negotiable certificates of title, bearer bonds, mortgages, and deeds of trust.)
The doctrines that demand a wet ink hard copy original for a will, and strongly encourage one for documents that will be witnessed, doesn't apply in the same way to trusts and corporate documents which don't have to be witnessed and unlike wills, are proof that a legal action was taken, rather than embodying that legal action physically. Copies of these documents and counterparts of them are acceptable.
Wet ink originals are also strongly preferred for any document with a guaranteed signature (e.g. many life insurance and securities transactions) rather than a notarization, and for documents that are likely to have historical value (e.g. an original city charter).
The first option is preferred one and the best practice
The preferred way to file documents executed in counterparts is option A:
Each countersigned copy (the complete document, not just the signature
pages) be stapled as though it were a complete document (even if it is
missing some signatures) before being placed alongside the others
This is because that is the most definitive proof that each person signing it in counterparts was signing the same version of the document.
What kind of ink and paper should be used?
The best practice is to sign originals in blue ink, which distinguishes them from black and white photocopies, or copies printed on a black and white printer. Pencils should not be used because they can be erased too easily.
It is likewise the best practice to use a superior grade of paper for the originals, rather than just ordinary copying machine or printer paper. The client will often have paid thousands of dollars to have this document personally drafted for them. Why skimp on the paper it is printed on. Also, this makes it easier to distinguish originals from copies.
It is almost uniform practice, however, to use letter sized rather than legal sized paper for estate planning, trust, and corporate documents. Legal sized documents were mostly a cheat to reduce the recording fee for the document which is now rarely material relative to the entire transaction, although some localities still use legal sized documents for certain parts of real estate transactions.
The envelope that the documents are kept in should have ample room to fit the complete document or set of documents, without having to shimmy the documents into it, and should be reasonably sturdy, and have a resealable closure, for example, with a piece of string around a paper button.
How should the documents be bound?
A related best practice followed by paralegals and legal secretaries in the better transactional law firms is to staple originals with a different orientation (e.g. diagonal) than copies of documents or printouts of scanned documents (e.g. straight and parallel to the top of the page) in a consistent way so that you can tell at a glance whether you are working with a copy or an original. It is also better practice to put an inked "copy" stamp on packets that are not wet ink originals.
Two hole punching and pinning the document or set of documents down with a different colored, heavier paper backing is an acceptable alternative, although a bit old fashioned.
When and why to scan the documents
This said, you should scan and electronically save a copy of each document that will be stapled or two hole punched before it is bound, so you don't have to damage the original to make a copy.
And, for many purposes, a scanned electronic copy is sufficient or even preferable, such as for providing copies to back up fiduciaries or beneficiaries or closely held business owners.
A single body text with multiple signature pages is not optimal
Option B probably doesn't fall below the standard of care to avoid malpractice, but is not a "best practices" approach. It leaves room to question if the counterparts signed were really identical, when it is often plausible that intentionally or accidentally, signers could have signed a version that was a not quite final draft of a document.
I've had a couple of transactions over twenty-five years where this was done intentionally by a dishonest counterparty.
Don't use binder clips for documents you are storing indefinitely
Option C is less desirably, because it doesn't take much of a mishap for a document bound by a binder clip rather than a staple to escape its binding and become scattered with its integrity compromised. Even diligent staff are going to jumble at least one set of documents every few months in a busy office if you do that. It is an accident waiting to happen.
If nothing happens to a particular set of origins, it is no harm, no foul. But if your firm loses a critical page of an executed trust or corporate document governing tens of millions to billions of dollars of assets, at a time when it is needed in litigation, there will be hell to pay.
Binder clips also tend to rip some proportion of envelopes into which binder clipped documents are stored.
Binder clips are great for holding together draft documents while they are being reviewed and revised, but are not well suited to storing final versions of documents.
Should the firm retain custody of the originals?
Honestly, most firms don't retain custody of original documents. It is more common (and wiser, most of the time) to keep a copy and a receipt for the original, and then to send the client on their way with the original.
Individually, it may seem like it makes sense to have the firm keep the originals. But if the firm disbands, in the case of a small firm, often due to the death of a critical partner, and in the case of a large firm due to some sort of merger or mass staff raid (as happened within the last year to one of the largest and most established trust and estates firm in the state, in a matter of days with almost no warning to some of the partners there), finding every single client to restore their originals to them can be very cumbersome and frustrating.
I once handled a probate estate for an estate planning lawyer with about five hundred sets of original estate planning documents in his office, and it was not possible to lodge them with a court because of construction and space availability in the courthouse. It was very cumbersome.
What should be done if the document must be filed or recorded?
If a document must be filed or recorded, however, the firm should do this before returning any originals to the client. This insures that it gets done. But there needs to be absolute clarity within the firm over who is responsible for getting documents recorded or filed after they are signed in every single transaction.
A firm I work with from time to time once sued the biggest law firm in Colorado for about $100 million in malpractice damages, a few years before I had done any work for them, and won. This was because the large law firm had failed to be clear about whether the senior paralegal or the junior associate attorney who worked together on the large business loan closing which was right before a long holiday weekend, was going to file one of the documents in the secretary of state. Neither of them did and this allowed a third party to get a higher priority lien in the assets of the business, depriving our client of almost any ability to have their $100 million dollar loan repaid.