I don't really have the ability to do anything other than what Yahoo allows.
If a player gets called up to the major leagues, they are no longer considered "NA", just like if a player comes off the disabled list, they are no longer considered "DL", so you would need to drop someone off your 25 man roster to continue to carry them.
If it's just too much of a burden, I'll trade you for Mazara.
On the transaction limit, picking up 3 free agents during the week doesn't seem too unrealistic. Moving Mazara up to the major league roster and dropping a bench guy doesn't count towards the number, I believe it is only added players. But like always, we will monitor it throughout the season and adjust as needed.