It would be very nice if different claims could create alliances with each other. Meaning that if someone from another friendly claim entered the other, it wouldn't flash red as if they were intruding. It would also be lovely if the friendship could allow members to come and help out, perhaps not in the same extent as that would give opportunities for other claims in the alliance to ruin for one claim.
One could set it such as a list in the monument, where one can send request, remove and change what kind of changes and help the other claim is allowed to do.
Mounterra - [x] Terraforming [x] Access crafting etc.
The Castle - [ ] Terraforming [x] Access crafting etc.
Fisk'vik - [ ] Terraforming [Access crafting etc.
Or one could set these for certain members within the claim and within the alliance, to allow certain trustworthy to have access to the other claim.