depending on your community, you might not even be in a position where it is an issue.
If you are chassidic , you likely married into another chassidic family and such issues would not likely occur. People are more homogenenus
Before praising the shidduch system, You are going to leave people out who are converts and BT’s. A Rav who was asked would likely know these factors. Before saying “Most of us would not want a heter” most would not marry a BT or a convert either where such issues are more likely to come up. Family relationships are more complicated when there are BT’s and converts (Doesnt mean they are bad, just more complex and those issues can usually be worked out)