Plan A: Sign Bo Bichette (probably not likely)
Once Bichette is off the table, go to Plan B, C, D, ...
I would say Plan B is to trade for a 3B. At this point, BOS could offer Duran or Abreu + Bello, and not really create a hole in their everyday line up or pitching rotation. That is a lot and should return a very good player and likely some prospects. Not sure who to target exactly but if they are able to do that, the line up could look like this:
1B Contreras
2B Meyer/Campbell Platoon
SS Story
3B New Guy
LF Anthony or Duran
CF Rafaela
RF Abreu or Anthony
C Narvaez
DH Casas
With the pitching that they now have, that is a decent team. There are too many LH hitting outfielders (Anthony, Abreu, Duran, Yoshida). Got to move one of them, at least. Another RH bat for the bench would be useful. Some one who could play a position plus some DH against lefties.