Best practce for calling functions between models

[eluser]mact1079[/eluser]
Since I'm pretty new to MVC frameworks...

I have a Users_model function addUser which inserts a user record into the User table based on the info they inputted in the registration form.

I also have a Invites_model functions createInvite and addInvitewhich creates and inserts an invitation record into the Invitations table for the same user.

I want all this to happen when the user creates an account.

Is it ok for me to call the Invites_model function from the Users_model to complete both table inserts?