Bunked in with the in-laws for a few weeks while we are between houses.
They have zero internet connectivity though the house other than wifi and I'm setup at the opposite end of the house, so cable run is not an option.
After some head scratching and some trial and error, I came up with a suitable solution
1 AP is connected to unraid, the other AP is connected to my routers (WAN port) that is then connected to inlaws existing router (LAN port).
This way I can get wireless connectivity to my unraid server, but also preserve both our existing networks.
Other than some minor issues that come from the extra network overhead, its actually working quite well.