Typing "share the gospel" into the search feature and selecting "titles only" will retrieve some older threads that have become buried over the years. However, I looked and saw that most of them did not get many replies other than one with the idea of sharing the gospel with Jews. The other threads the engine retrieved either didn't attract very many replies or weren't exactly what you are looking except maybe one that you could bump back up with a new post and revive the topic.
https://christianchat.com/threads/sharing-the-gospel-with-your-family.48725/
I assume you were thinking of sharing the gospel in general, but I figure that bringing sons and daughters to God by sharing the gospel applies as a "family" topic.

Gal 4:4-5