Sociable children tax mom’s hosting talents

Dear Amy: I’m a mother of two children, ages 7 and 10.

My kids enjoy playing with their friends outside of school, and I mostly don’t mind hosting playdates.

We do way more than our share of hosting, however.

One of my son’s best friends is frequently invited to our house, but rarely reciprocates.

The mom even acknowledges that they “need to have him (my son) over,” but the invite never seems to arrive.

This mom is busy (she has three kids) and rarely turns down our invitations, but rarely invites my son over.

Short of inviting ourselves to their house, is there a way to politely ask them to play there more often?

I get tired of having the same kids over and rarely getting invited back, but I don’t want my son to never get to play with his bestie, either.

Should I…