The 28-year-old singer welcomed his first daughter, Alaia-Mai, into the world with The Saturdays' star Rochelle Humes earlier this year but doesn't think 25-year-old Aston is ready to look after his little girl just yet.
When asked if his former JLS bandmates - Aston, Oritse Williams and J.B. Gill - had been helping take care of the four-month-old, Marvin told BANG Showbiz: ''Not yet, when she's a little bit older ... They will do though ... Uncle Aston last because he's still crazy. J.B. and Oritse first and uncle Aston when she's a bit older.''
Marvin also isn't sure if his boys are up the challenge of changing nappies.
He said: ''I'm used to it so it's fine ... I'm not sure they want to really have the baby just yet.''
The R&B group - who found fame after finishing second on 'The X Factor' in 2008 - are set to split later this year but are confident they will remain friends after they go their separate ways.
Oritse said: ''We've always said that we're brothers, bandmates then business partners. Brothers comes first because for us we came together through a love of music and a love of the same things.
''We're still meeting up and we're still going out and that's going to continue. Our families are all one big family as. Family is family and that doesn't change.''
JLS will be releasing a live DVD of their concert at The O2 in London and 'Goodbye - The Greatest Hits Tour DVD' is available to pre-order now.