As I understand it, teams can now make roster transactions. (after noon ET today)
From the Gelb link above, he clarifies the 60 man pool timing.
> The Phillies must submit a list of 60 names eligible to participate in the 2020 season by 4 p.m. ET on Sunday,
So it seems that decisions have to be made now on which non-roster players and which minor leaguers to add to the pool from which the active roster will come for the upcoming season.
Another thing I learned from the Gelb article:
> When the Phillies form their 60-man pool, they do not have to include all of their 40-man roster players.
As an example, he points out Dominguez can go on the 45 day DL and open a space in the pool as well as a 40 man roster space should they need it to add someone later.
He also points out that some may opt out of their contracts is not on the opening active roster. They can be replaced from within the organization.
> ....once some veteran players on minor-league deals realize they will not make the 30-man roster for New Opening Day, they might ask for their release. Then, the Phillies can add some younger players from within the organization to the 60-player pool.