Hi Dev Hope you're well. Why not ask Pyramid Consultants (the PECS people) for their recommendations? They have Julia and Louise who work for them, both of whom are s/lts by training. If you go with them, (both very nice people) you will get everything you want in one package.
I am thanks. Pyramid offer all sorts of training and would be happy to put together something for your specific needs I am sure. You would be guaranteed an excellent service which you aren't if you pick a generic s/lt who says s/he is an expert in ASD and PECS. Most s/lts don't understand how to use PECS properly and most certainly aren't ASD specialists of the kind I know that someone like your family would want.