Am I entitled to sue for a posted bail value if the bail was forfeited?

My guess is NO but then you can sue any one for any thing but that does not say you will win. As long as he/she is in the hokey-pokey you would have to wait for them to get out to defend them selves in court. I would just write it off as a bad investment and don't make the same mistake twice, even if it is a relative.