Dissolve Alliances via Hacking Home Systems

While stealing technology is already strong, the destroying alliances hack would be too strong and thus a horror to balance, it has only a pretty low chance to get implemented.

Hm... I don't think distrupting an alliance for a few turns (which, according to the idea above, can be countered by paying influence anyway) is "too" strong. 

Also if stealing tech is "strong", that means you have to sacrifice "something strong" in order to distrupt an alliance. Seems a balanced trade to me.

Ho boy yes that's too strong. When an alliance end that also end any diplomatic exchange between those factions, reseting their progress into those. (I'm talking about the comercial/production/science exchanges.)