Hello Rebeccaclaire
Regarding Crests, Fairbairns Book of Crests Volumes 1 & 2 are interesting, the researcher needs both Volumes.
Volume 1 with Descriptions and part of the Plates Index
archive.org
Volume 2 with other part of Plates Index and Plates of the Crests
https://archive.org/stream/FairbairnsBookOfCrestsV2#page/n29/mode/2up/search/CoeIn the Plates Index the first number denotes the Plate and second number relates to the Crest.
1) A Coat of Arms did not really evolve within a family for change sake. A Coat of Arms were usually granted to a particular named person. (See 4. below).
Dad said many were granted for a particular favourable Act to the King or Queen. One in Newcastle I read about was granted Arms for Guarding Parliament.
2) "
One of my more recent Popham ancestors in 1725 used a seal on a property document that was described as 'armorial, three chevrons, not determined.' Do seals link to families?"
The Seal is only a part of Arms. I have seen Seals in the Crest (in the Arms above the Shield).
Seals on their own might not be enough, as differing family surnames had the same Seals. See Fairbairns (both Volumes).
3) For the first 200 to 300 years backward from yourself, you might as well have the fun and interest of going back yourself.
Have you considered an appointment at the College Arms to do some research? Keep all your copy Certificates, Documents, Wills, etc., linking each generation backward from yourself.
4) "
Could families hold multiple coats of arms? ... "
Coats of Arms were designed for a particular holder, to whom they were Granted.
If the College of Arms, Grant Arms to a Cadet in the same family (see Cadency), these Arms usually vary to reflect that they are not the original holder and will have different marks in the Coat of Arms.
5) You will only find the Coat of Arms, and if Arms were Granted to a particular line ancestor and the person to whom they were Granted, by working your own personal family line backward.
Not everyone in an Armorial family can quite make a link, perhaps a Sibling of a direct line Ancestor was Granted the Arms.
The College of Arms (never been there), must have numerous Volumes of Indexes and Coloured Illustrations of Arms Granted to individuals and submitted family lines.
I notice Rootschatters refer to Wills, that mention Arms and the original beneficiary informed the College of Arms and if Granted, Notices appeared in the London Gazette.
6) Other sources - Victoria County History VCH (published about 100 years ago), can be a useful source as they give references to documents, which you can trace in Archives.
Sometimes you can find people mentioned in:-
Manors, Land Owners and records of Lords of the Manor, Estate Surveys, Rentals, Accounts, Deeds, Leases, Tithe records, Old Maps and Schedules, Fee Farm & other types of Rent, Tax, Land Enclosures, Court's Baron, Manor Court Rolls, Marriage Settlements, Parliamentary Acts, Court Documents, Exchequer cases, and the like.
Many Lords owned land in many counties and their collections today are spread over several County Archives, Museums, University Special Collections and National Archives and National and Principal Libraries, some are still in private hands.
Mark