Buffalo easily declines

what would you think they need to add or substract to make it work?

It probably wouldn’t work for 2 reasons.
1 Marner makes more than Eichel somehow they probably don’t want to pay a player over 10.
2 they have to sign Dahlin to a big contract next year.

If you throw in Okposo?

He probably wouldn’t waive he has a family that lives full time in Buffalo.

https://www.google.com/maps/dir/Buffalo,+NY,+USA/Toronto,+ON,+Canada/@43.2681849,-79.9141971,9z/data=!3m1!4b1!4m14!4m13!1m5!1m1!1s0x89d3126152dfe5a1:0x982304a5181f8171!2m2!1d-78.8783689!2d42.8864468!1m5!1m1!1s0x89d4cb90d7c63ba5:0x323555502ab4c477!2m2!1d-79.3831843!2d43.653226!3e0

Hahahaha. That's what I was thinking! Okposo has a 15 team no trade list. So it's not a situation where Buffalo would have to ask Okposo first if he wants to move to Toronto or not. He'd first have to have Toronto included on his list. If he doesn't want to move too far from Buffalo, well....then his choice is pretty clear.

For the trade, yea it's not the best for Buff because of money and giving away a good prospect in his cheap years.
How about Marner (2 Million retained by Tor) only for: Ristolainen, this years 1st rounder (8th overall)?

I can see that working

why would Buff trade a top 2 defenseman on a entry level deal, 8th overall and a potential top 15 pick for a horrible contract a career Ahl-er and a defensemen we have no use for

I am not sure if this is enough to be honest. especially when retaining money on it.