Trying to share a contact group on iPhone?
This doesn't work on Chrome for Mac, so it may be the same on Windows &amp; require that you use a different browser to achieve it...


Go to https://www.icloud.com/#contacts  
In the left column, select your required group  
Gear menu, bottom left -
Select All, then
Export vCard




The exported file contains all the contact details for that group of contacts.
This can be shared.

Whether that data can then be used to send a single text may be dependent on your carrier.