Field for Secondary Cell Number or Per VIN

Here is a scenario - A father and daughter have both of their vehicles on one profile because both are under the ownership of the mother. The daughter has an appt that we sent a text for but it wound up going to the mother since the cell field is the only field that allows a text. I want to be able to text more than one number, and know who they belong to.

Perhaps even a cell number per VIN which could easily be picked up with batch jobs as well