Is it possible to program a feat to allow a multi class character to advance a single power of a class similar to the increased caster level feat/trait line.
For example:
Summoner 1/cleric 3
Feat:
Fancy name
Grants +4 class levels for summon monster SLA up to the HD of the character. All normal restrictions still apply to the use of said power.
I'd see this similar to eldritch heritage, but instead of outright gaining the class features of the sorcerer bloodline, it would only increase if the character already had it.
For example:
Summoner 1/cleric 3
Feat:
Fancy name
Grants +4 class levels for summon monster SLA up to the HD of the character. All normal restrictions still apply to the use of said power.
I'd see this similar to eldritch heritage, but instead of outright gaining the class features of the sorcerer bloodline, it would only increase if the character already had it.