My DH has 2children with his ex, and we have 2children together, his 2children - my step children live with their mum and come to us at weekends... Well the younger of the two has been staying with us for about 3/4 weeks now and has more or less said would like to stay with us permanently and just got to mums house every 2nd weekend....DH and I did not see this coming, and we said to have a think about it before making any rational decision, however every day since was brought up, it's still said DC wants to stay with us, so Monday evening my DH went to see his ex and inform her of DCs choice wanting to stay with us permanently.... Ex was taken aback and very shocked and wanted to know why/ had she done something wrong for this to come out the blue....anyway Ex has now said nothing can is happening until all sit down and talk, so my DH has asked if could talk at weekend as she's working, off at Weekend.... She said will sort something sometime, needs to sort her head around this....I get that I do, but at same time, surely as a mother you'd want to know and try sort something out sooner rather than later. DC has been with us these past few weeks as we hadn't seen during lockdown for reasons in relation to covid, DC was meant to go back to mums the other evening but asked if could stay longer and said to mum which she agreed too as was working all week so older Child who's 17 would have to look after DC who is turning 13 in a few months.
How would you approach this subject?