Which FA RBs to stash/swap out?

Currently looking at Mattison, Darrel Williams, Pollard and Jamal Williams as FA’s and wondering who to add.

My RB core is Kamara, Jones, Montgomery, Ingram, Singletary, Drake, Brown. Full PPR.

Would you drop Drake (he’s not getting traded is he…) for Mattison now and hold him. Also would you put Brown down for Darrel Williams, Pollard or Jamal Williams. I’m getting nervous about this GB timeshare so may just keep trying to sell Jones, and not sure if I want to drop Brown but the Rams ground game looks very average this year…