Quote Originally Posted by evo76 View Post
Hi, anyone who has an idea on how to make a supporting letter for soon mother in law who is a permanent resident in United States?? help please
Hi Evo, welcome in here
To your question - try to take a look at following website, hope it will help you with application:

UK Visas - INF2 - visitors

And according to this information (Where to apply - US) her only option is to apply online and then submit biometrics at one of the centres.

Good luck