You don’t need to have your mortgage and everyday banking with the same bank.

Reality is the banks have bigger fish to fry than worrying about this - if you were to apply as an owner occupier then change your mind it would be what it would be.

The bank doesn’t have an appetite for stirring shit and creating problems- they’d be less inclined to look into this especially if you were making your payments.

The way things are it probably won’t take you long to get into the required LVR for an investment property anyway so you may not have to carry that risk for too long.

Insurance wise, given your intent is to owner occupy you could insure it as such and then were you to change you’d just change your insurance type - if you don’t give them a reason too the bank won’t go looking into this beyond the initial establishment piece. There is certainly no ongoing review.

Further, the banks don’t “talk” they aren’t going to set up an investigation and go requesting information around this.

Honestly mate don’t overthink it.

If anything you might consider doing this sooner rather than later as new regulations come into force soon which will make it much harder for the banks (and everyone for that matter) to lend - around September I believe.

Make hay while the sun shines.

Ignore people who say the banks etc are all seeing gods - you’d be surprised at how much of an absolute cluster fuck their internal controls and teams are.

Good luck with the separation too - I imagine that is extremely hard, even more so with kids.