To give DSS 5k only for wedding

[mymonkeymycircus]

My DH has a son from previous relationship. DSS mother died years ago and DSS inherited quite a substantial amount. His future wife is from a well off family and both DSS and fiancé have well paid jobs.

They are getting married and we've managed to put 5k together as a gift. Is this enough? We're not well off but want to keep up with expectations.

Is 5k reasonable or AIBU?

I would expect to cover the costs of the family guests at the reception and a bit more perhaps, that seems more than generous though. If aren’t expected to invite great aunt Gladys uncle Tom and all your kids then maybe give less.