I was wondering if a noble would take his family's crest and modify to fit him more personally, (i.e. family crest has a loin, he replaces it with a dragon, different color lion, etc. etc.) or was he stuck with the family crest until he did something of note?
Could he make a new crest and split off into his own branch of the family?
Hi, it may be worth specifying which region and time period you're asking about, since customs may vary, but meanwhile you may be interested in a few posts on heraldry:
Did noble families in the middle ages have a family sigil and/or motto like in Game of Thrones? featuring /u/QuickSpore and /u/tim_mcdaniel
Heraldry and Livery featuring /u/deMohac
How did families get their crest's and coats of arms? and How did knights prevent copying each other's heraldry? featuring /u/tim_mcdaniel
Irish family crests/coats of arms featuring /u/The_Chieftain_WG