Hello Brigitte,
I'm a speech therapist living in Holland. I'm treating a little boy (5 years old), he has OMA and severe speech problems like your daughter. He still has problems moving his tongue (after 3 years of therapy!), but he knowes enough words now and also his syntax is average. Some consonants he cannot pronounce (f,v,s) but the other ones are good. Most people can understand him now, but we practice twice a week the tongue-movements. It's a long way, but we will get there. Good that your daugther has learned signlanguage, that can help her a lot. Greetings, Bea.