National Team selections need to be made approximately 2 weeks in advance of any upcoming friendly matches or competitions.
The national team squad must consist of 23 players, meaning that in order to add someone, another player will need to give up his place.
For international friendlies, you are free to change your squad lineup for each match.
However, this does not apply in the case of international competitions where changes to the squad cannot be made once the competition is underway