All of these seen recently.
I suppose there could be a plan to do nothing (an inaction plan?), but generally plan implies taking action — so the first element inaction plan is redundant.
Betwixt and between
They mean the same thing.
Yes, the phrase is used idiomatically to mean ‘at a loss’ or ‘unable to choose between alternatives’, but it has no place in legal drafting.
Just between in your contracts.
A thoughtful reader points out that the –ship bit adds nothing.
Compare trusteeship or fellowship, where the suffix actually changes the meaning of the other part (turning person into thing).
In the realm of dating and marriage, relationship is now too entrenched to be dislodged; but you could usefully use relation (orrelations) in your legal writing and drafting to describe the interrelatedness of parties or concepts.
The actual phrase used by an American professional development manager was skill sets for tier levels of associates. Insert Edvard Munch ‘Scream’ emoji.
There’s a lot of redundancy going on there: just skills would work (and sometimes those come singly, not in groups); and either tiersor levels, but not both.