You don't need the word "たぶん" which means "probably" (Unless you think you might not actually be able to do this based on something that's happening on your end? In which case, more information than just that one word is needed).
If you want to convey a sense of "if possible", then a better word choice is 出来{でき}れば
Or you could say "if you have free time", which is: 時間{じかん}があれば
The rest seems ok. I'm not sure how emotionally close this family is to you, but if you want to convey a more "formal/polite/respectful" suggestion to them, しませんか sounds less "pushy" than しよう.
Not that しよう is necessarily bad. It's fine if you have a very close and friendly relationship with them.
As pointed out in the comments below, instead of 食べに会う (meet to eat), which though understandable is less natural, 食べに行く (go out to eat) is a better, more natural word choice.
出来{でき}れば、一緒に晩ご飯を食べに行ったりしませんか?
時間{じかん}があれば一緒に晩ご飯を食べに行ったりしませんか?