What's the rule on this? I know that a player can enter another for singles as well so if someone says:
In and doubles with X, if X doesn't come and enter for singles I assume they want to play singles too and have told the partner to enter them.
Another player can commit for you but this has to be said clearly.
If you just say "in and doubles with player XXX" that´s not enough for the manager to put both players in the singles entry list.
In fact there are players who only play doubles and who don´t commit at all to the tournaments they play, because their partner commits their doubles team.