Before we go any further, we need to positively identify the surname of the G-Grandfather that you mentioned in your query. By normal procreation, you would have had a minimum total (without any second marriages) of four different (usually) surnames involved with the sides of both families involved. (See attachment) By the way, we're talking about 'Arms' (the shield) here and not the 'crest' - the crest is the thing that sits on top of the helmet which can change from generation to generation.

If the G-Grandfather to whom you are referring happens to be Male-4 on the chart (the same surname that you were born with) then there may be a link to the particular coat of arms. However, if the G-Grandfather to whom you are referring was Male-5,-6, or -7, it is unlikely that your brothers would be entitled to use the arms. If Male 4 had arms, then Males -1 and -2 would also have been able to use those arms. Arms are transmitted through the male lineage because the name to whom they were registered/granted in the first instance stays with those arms.

If an Armiger (person who has Arms) does not have any sons, his daughter/s (if any) become what is termed 'an heraldic heiress' which means that she, and any sisters, are equally entitled to inherit those arms for themselves. They can then pass on those arms to their children as long as their respective husbands also have arms. If the husbands do not have arms themselves, the arms become extinct as those arms can only be passed on to their children as a 'joining of two sets of arms in marriage'. This is a fairly complicated area of heraldry, so we need to determine just who it was who supposedly had arms. Once we have determined the actual surname to whom the Arms were granted, unless it is Male-4, we need to determine the family structures in between you (and your brothers) and the supposed Armiger.

If you can determine just who is who in relation to the attached diagram, we might be able to provide you with some further assistance. Till then,

Regards,