Asking Allah at such places is an innovation and means to fall into shirk.
One should make it clear to people that this is prohibited.
I believe that one must stay away from such people and not engage with them in marriages.

my friend told me their family visit dargah but they don’t ask the wali there for his waseela or something they want instead they make him their wasela and ask standing on their graves from ALLAAH to bless them with certain thing. How’s it then ? Should anyone marry in this family ? Is it okay to give anyone into marriage in such a family?