surname?

so me and my hubby have got children from our previous marriages. my children have my surname not their dads and his children have his surname. we are currently pregnant with our first child together and we are struggling to decide on the surname hes said hes happy for the baby to have my surname so its the same as my other children but i feel like thats taking away from him and also feel like its separating his children from the family. we discussed double barrelling which i think is the decision so far but both our surnames are quite long and we were hoping to have 2 middle names like our other children have so i feel like it will just be too much? any opinions ideas etc?