The boy's passports and legal surname

It has occurred to me that the boy's passports expire in Dec THIS year.

My passport expires in the next 18 months. When I renew I'll need to get one in my Maiden/Current name. (I am still using married name passport)

Which brings me neatly back to:

1. Trying to get their names changed (I've all but given up on this)

and then

2. Renewing their passports

Both of which require paternal consent and approval. And most recently it seems the father is actually meant to be present to apply/

Ideally I should get their new passports in the Fraser name, because if I have a different surname to them I will (apparently?) face more of a challenge when trying to travel across borders with them.

So from an objective point of view. Do you think I should try to tackle this anew with dearest bio-dad who up to now has not been willing to do anything at all about anything? (To do with either me or them??) Or get approval from his mom and an affidavit to say he is MIA and unable to provide consent himself..? Would that even be accepted??

Any other ideas? Otherwise we are stuck in SA until they are both 18/21!???