I get why Senators asking about Weegar and Andersson, but both guys are valuable and more valuable to the Flames than perhaps the Sens. You won't like the ask because it's more than they're worth, but honestly, that's kinda the size of the hole and inconvenience if they were moved off our roster.
Andersson is likely next in line as Captain, so it's no thanks unless the guy in return is also high talent and captain material.
Weegar is a top pairing RHS LD and a local Ottawa guy, but can play 2nd pairing RD (his off side) as needed. 3/4 RD alone aren't cheap and top pairing guys aren't cheap. You'd get a weird hybrid of that if you acquired Weegar and we'd be in a situation where a guy on his off side (ie: Chychrun) would be of lesser calibre than Weegar on his off side.
But I get it. The Flames have tons of great options that might help Ottawa develop their young guys well and improve in their standings. But the UFA expiry is too short (for current season) or duration or cost are all hard pills to swallow for Ottawa. The experience, cultural and style fit seem to fit. But the types of assets and asset types and contract structures make it hard to facilitate a deal that works for both sides.