How to get Cortana to use a selected phone to send a text?

[Windows Central Question]

I have 3 Window phones, 2 test for Windows 10, and the other with
8.1. The 8.1 has the SIM card and I tried to send a text using Cortana
on the PC, running Windows 10, but it selects a Windows 10 phone without the SIM to send the message. How can I get Cortana to use
the 8.1 phone?

 

[PepperdotNet]

The texting feature from Cortana on a PC only supports Windows 10 phones.