co habiting stbx

[Dirge]

I've got a CAO in place, but the financials are not sorted yet. From what my kids, and others, have told me, stbx and kids are more or less living at the stbx's partner's house. On top of this, It is galling to see this scumbag partner using my stbx's address like he owns it, when technically the house is still in my sole name, but guess I just have to suck that up. However, I believe that if stbx is co habiting with a "new" partner, this would have a significant effect on the financial settlement. I think co habitation would probably be difficult to prove but does anyone have an idea of what the standard of proof would be?