I admit I am responding perhaps in haste, but I'm not sure this is against the rules that IceBlack has pasted here. Maybe after I'm done typing this post I will have changed my mind.
First, we are talking about what is legal for the JV team, not the team of 8th graders.
I don't see a violation of 4.1. The JV girls are participating as a member of their school, not as a member of a non-interscholastic program. The JV girls are not participating "in" a non-interscholastic program, they are participating against one.
4.3 is not so clear. I would argue that for the JV team, it is a scholastic contest since it is for their school team. I would argue that the meaning of non-interscholastic is that the high school player can't play as part of a non-interscholastic team, not that they can't play a non-interscholastic team.
I think my arguments are reinforced by the bottom part of IceBlack's post where he/she posts the part of 4.3 of participating in non-interscholastic programs - team sports. The gist of it is that high school players can't participate "in" those programs during the school season, not that they can't play against those teams.
So, I haven't changed my mind, I think the scenario presented by zips15 is legal for the JV team. I would call the OHSAA to get its interpretation, though. I have more confidence in my own analysis than anything the OHSAA might say, thank you very much, but the OHSAA will be the one whose decision counts, so I would listen to it.