Don't really see the reason why these trades would work. A trade is always preferred to an offer sheet. The trade here would be attempted first for Brannstrom and if Otttawa wouldn't take it, the offer sheet would follow. Same way Kotkaniemi worked.

It is legal i think as previously ( albeit more in the 90's ) teams traded the compensation they got back to it's original team for other assets

i agree with your point, but this is hypothetical if it would be allowed

so you want to give OTT the 3rd rounder to compensate the offersheet.
and then trade other assets to get that 3rd rounder back?

it's legal, but unlikely,

i think the teams would rather just trade the assests for the player.

i think the OS needs to be in the 2.5-3m range for the sens to consider not matching, the trade is the same where it just needs a bit better of a piece for it