My dad did this to me and my mum. Foreign holidays, jewellery, custom cakes and ponies for new family...abuse and threat of homelessness for us.
On the one hand, he was able to declare himself bankrupt and the house was repossessed.
On the other hand, the threats of homelessness and cessation of payments started when I was about 8 but the house didn'tget sold til I was about 20. And my mum got half the proceeds, and we got a secure conscious tenancy in a respectable area, that later my mum was able to buy (which turned out to be the same value as the home we were forced out of).
My mum fought like a tigress possessed. Long, hard, fierce, on every front she could open and with every bit of help she could find.
In short, she can make it much more troublesome for him than it needs to be.
This was in Scotland and happened 20-30 odd years ago, so laws might differ and things have changed, but off the top of my head:
Find a good lawyer. One that will fight, keep going til she finds one that will fight. Might even be worth consulting an insolvency practitioner from another profession, e.g. Accountant, or a forensic accountant if she can afford it.
Access every bit of help she can from advice bodies- Citizen's advice, Consumer protection, Shelter, Gingerbread.
Your friend should make whatever payments she can, whenever she can. If the bank is getting there money, even intermittently, even if it's just the interest, it might slow them down.
Check with his professional body if he is allowed to practice as a bankrupt- some professions aren't. If he is a partner in a practice, that would have to be sold or given up as part of his bankruptcy. He isn't allowed to act as director of a company without telling the court- his fellow partners might not be comfortable with that.
Involve Women's Aid, Child Support Agency, local,social,services (threatening to make his ex and child homeless is emotional abuse- now a crime)
Get and keep as much evidence as possible of his financial dealings. From financial records of the GP practice where he is a partner, to marital financial records, to Facebook posts boasting of holidays etc whilst he is claiming poverty. Courts have discretion over how long remains bankrupt- evidence of profligacy might count as non-co-operation with the trustees).
My parents got divorced when I was 13- so 5 years of court battle for the divorce. Then the battle over the repossession of the house took another 7 years.
One of the most important things my mum did was refuse to actively co-operate with the repossession. She fought that herself in court and made payments as she could. The outcome was that the house had to be marketted for sale but wasn't repossessesed and auctioned.
She also would allow viewings, but only once the court ordered her to. Her argument was that she could be expected to co-operate, as that would make her intentionally homeless, and the local authority would then not have a duty to rehouse her. So she made what payments she could (I got a part-time job at 14 and started helping out), she didn't actively help or actively hinder the bank.
Basically, any spare money we had went into the mortgage account, not on (minor) repairs that would make the house more attractive for sale. It was on the market for over 6 years. Everyone locally knew the circumstances. Lot of people wouldn't go near it for sympathy reasons. Others because it might fall through due to legal challenges/delays and somdisrupt a chain. There was a slump in prices anyway. The house was in a bit of disrepair, so wasn't attractive in buyer's market. Finally it did get repossessed, and the bank marketted it, but we got a good council house and my mum got 50% of the equity in the house.