I know a family who has seven children. They're Irish Catholics, which seems to make most people think the worst when I mention it. However, the parents are both doctors and are able to support the kids adequately - they are a super family and I'm always pleased to bump into them.
I don't have a problem with large families under these circumstances - the parents are responsible and absolutely not a drain or a burden on anyone. They have been prepared to make material sacrifices for their kids which, from what Maggie has said, her daughter may have difficulty doing.
I think, Maggie, it's up to your daughter to tell your hubby. Why should you have to take the flack? When he's calmed down, I think all you can both do is just let her and her partner get on with it. Sooner or later, they will realise they can't have everything. Hopefully they will then make the right choice.