Because you are a CP, you will probably be able to use the DBC voucher for him without him being in your family.

Now, with regard to return, yes, of course, he can standby on the PALL list but not with your status. He will be a SB4. Except for SB1 - SB3, depicting preferred DM/HP preferreds, ie CP, GP, SP which will list ahead of him, the best thing is to the get to the airport early as it's pretty much first come, first served on the PALL list with a SB4 designate.

Hope that answers your question.