Welcome to the forums, Damianus_NT.
If you are playing MOS, then this is the right thread to ask questions.
Not much that can be done about AI behaviour, I'm afraid. The dwarves are probably the most difficult faction for the AI to handle, as their territories are so far apart from each other.
The things you describe are not that uncommon, it is one of the weak points in this game. The only thing I know of that
may help is to make sure a faction (in this case the Dwarves) has territory directly adjacent to the region you want to gift them. If they have to cross other lands to get there, it is very unlikely they will do so. And there is of course always the rather big chance of the settlement rebelling before a new owner gets there.
In case of attacking other factions it is a similar situation. If a faction does not share a border with a faction they are at war with, they may very well do nothing. Especially when the factions they do have a border to, are stronger.