You're right, definitely lots of siblings! So far, I haven't been able to track down any marriage records to Clara. If I can locate one, then it might list her true maiden name, parents, etc. I'm going to keep searching, but in the interim I found a couple 'potential' threads to follow on Clara BROWN (b. 1875 in Indiana):
-- Parents: Susan Durant & Thomas Durant
-- Parents: Sarah E Primous # Joe Primous
I don't know if either of these listings for her parents are correct, but they're at least another path to track down.