Kinda "cause and effect" with emphasis on having a plan B, depending on the effect??
Yeah, exactly. Like "if enemy main attack is on this axis of advance, then do this...if main attack is on the other axis, do that instead." Exactly.
That's a branch, by the way. A sequel is more like, "if we have greater than expected success, rather than consolidating on the objective we will push forward to a supplementary objective further along."
Branches deviate, sequels follow. Something like that.
A single plan, especially at the higher tiers of command, can have several, even dozens, of branches and sequels.