I am really impressed with all your guys kowledge of history.
By us it was once noigea’ah so we went to ask a Rav and he told us,
a) only to do it if the siblings and spouses – potential mehcutanim – are not strong characters, as there is often a certain amount of disagreement with mechutanim, and if they are siblings it can really get out of ahnd.
b) to take care of allblood work and financial discussions before the couple meet.
c) he told us that if it looks good, it is really worht doing, because you already know all the chesroinois, and you are much better off than with someone that you do no know.