Ah, yes. Could limit it only to +1 rank, but my original suggestion was to pass an increasingly difficult Discipline check. Maybe difficulty should equal the #of desired ranks? That may make more sense.
Meanwhile, @Marlow on Discord suggested a simpler version, which I attempt to summarize below. Others there criticized my draft rule saying results in overpowered Force use, which this addresses:
Simple Skilled Force Assistance
Follow Skilled Assistance rules, by combining best-of Force Ranking with best-of force power upgrade(s). And if a helper has equal in FR and relevant upgrades, they add (commit?) a Force die to the roll.
For example:
a. two FR1 PCs with Move, silhouette 1, roll two Force die.
b. Or FR5 with Move sil 1 helping FR3 with Move, sil 3, rolls 5 Force die (2 extra from helper) to move sil 3.
c. FR5 with no Move skill, can not provide Force Move assistance.