Hi Sylvia,
I have a few ideas but first can you just confirm the issue is, to paraphrase :
'''There are two trees on MyHeritage which you want access to but the managers are not responding to your requests?'''
Because the MyHeritage trees are all private i can't imagine the MyHeritage staff just giving you access to those trees, no matter how nicely you ask.
One slow way around that sad fact would be to use Geni's Smart Match software, presumably you already have profiles on Geni for your mother's cousins. These profiles should have Smart Matches available for you to view which among other data show the parents and children of the profile in question. So checking the Smart Matches for cousin Wolfgang's profile would tell you the names of Wolfgang's parents, children and siblings, once you create Geni profiles for for these people Geni will automatically locate Smart Matches for them in MyHeritage. For example Wolfgang's father's profile's Smart Matches will tell you the names of Wolfgang's paternal grandparents who you can then make Geni profiles for. It will be slow going and you may lose some of the details but at least it will not be a complete loss?
Hopefully someone else will have a better suggestion.
Alex