Contact with SMS for Test but email for iMessages

Most of the family uses iPhones. One member is stubborn and wants to use Android. However, this same person uses an iPad. How do I create a contact or contracts so I can message the phone with SMS/RCS using my Messages but then also the iPad using iMessage?

I've tried creating a single contact with the Mobile being the cell number, then adding the email (which is bound to the iPad for iMessage). Then when I go to the contact, it won't let me send as SMS. It always sends as iMessage.

Any suggestions?