How do these work?

How do you add someone to your expanded roster?

How do you add someone to your playoff roster?

Does it count against a guy's ML years if he's never been in the majors before? In real life you have your September call-ups that dont count against ML service.

Thanks in advance.

Players have to be on your 40 at roster expansion to be added to the playoff roster.    There will be a "Playoff Add" option.

To add a player to your expanded roster, simply promote him to the BL.

It does count as service time.

Anybody on your 40 man roster can be added to your ML roster after the "Expand Big League Rosters" date.  Any time spent on the ML roster counts as ML service time.  I've always assumed that it works that way in real-life as well.  If you have a reference that says otherwise, please feel free to post it.  I'd be very surprised if that was the case.

Anybody who was on your 40 man roster as of the "Set Postseason Roster" date are eligible to be on your post season roster.  Your post-season roster is 25 players, but you can adjust the roster before each playoff series (but not during) to add or remove eligible players.  By default, the 25 players on your ML roster as of the "Set Postseason Roster" date make up your initial playoff roster.  It's not uncommon to change your roster for the postseason because you typically don't need as many pitchers, so you can drop one or two and add an extra position player to act as a D-rep, PH, or PR.

Time spent on the ML roster during the postseason does NOT count as ML service time.  Only regular season days on the ML roster count.

September callups IRL DO count as service time.