Building in castles with my builder

[Tukolp]

Hello there everyone,
First of all I wish you a wonderful day, and I hope you can help me with some information.

I have an idea which I would like to make for Edain and this idea is to add back builders to the game but use castle system still,
We would start with castles(or camps) but would be able to use builders to build buildings, and also builders would be used for farms.

I removed the buildplots from the castle, and made the builder work with the cuirrent buildings for the faction, but, I cannot build in the castle with my builder.
Although I am able to build close to the citadel with my builder in war of the ring mode, where the castle flag is not present, so I think something is with the castle flags code which is preventing me from my goal.

Also I considered another idea which would make us start with the "outposts" the flags with 3 buildplots, I would remove those plots and just put some defense expansions buildplots, but this mode would need walls which I'm not sure I want to mess with.

So I would like to keep my first idea which concerning using builders and camps and castles, so this one would be between the BFME 1 and BFME 2 buildsystem.

Thanks for your time,
and hopefully for your answer,
Wishing the Best,
Tukolp