Ideally, by the time of an engagement each person should have met the other person’s family. If not, do so quickly. A lot can be learned about a future spouse by meeting his/her family:)
According to the traditional rules of wedding etiquette, after the engaged couple has told both sets of parents about the plans, the parents of the groom should contact the parents of the bride and give their congratulations (for what, I’m not sure–that they are acquiring a new son?)
My FS n L’s mom sent a card with a picture of their family. I thought that was quite nice. I don’t think she said congratulations–actually, I felt like congratulating her because her son had won my daughter’s heart (LOL).
If the families live in the same town one set of parents might invite the other over for dinner or suggest meeting at a restaurant. This is a good way to get acquainted if you don’t already know each other.
If the families live in different towns (or as in our case) different states, things get a little harder. Depending on circumstances (distance, cost, convenience, etc.) one family might travel to meet the other family.
In our case we traveled to meet FS in L’s family because we had never met them, but also because our couple was going to live in their city after the wedding, and we wanted to see where they would be living!
Another thing you might think about is meeting somewhere in the middle between the two hometowns. Perhaps there is an interesting place to visit or a resort or nice hotel somewhere in the middle that would provide a pleasant meeting place.
The main thing is that it is important for the families to have met before the hectic wedding weekend begins.
There will be many things to discuss–after all your two families will be bound together for many years to come–sharing holidays, grandchildren and many other events.
If it is not feasible for the families to meet, at the very least the mothers should establish some form of communication–telephone or email.