Its Shelton vs Shelton (not Sheldon) and unfortunately I cannot find it to read the case myself.I hate to disagree with so many experts, but there appears to be case law in IN which supports OP's statement. In IN (according to Sheldon v Sheldon), there can be a justification that someone living in the same household can be considered a family member:
[url=http://haslerlaw2.blogspot.com/2008/05/following-up-on-parenting-time-right-of.html]Sam Hasler's Indiana Divorce & Family Law Blog: Following Up on ""Parenting time - Right of First Refusal"[/url]
Now, that's not a guarantee that OP's situation will meet the requirements. In particular:
"The practical outgrowth of this, included in the section's language, is that the best interests of the child are also served by extending the parental childcare preference to responsible family members within the custodial parent's household, also the child's household. As a result, the definition most appropriate under the rationale of section I(C)(3) is that "family member" must he limited to a person within the same household as the parent with physical custody."
If OP's BF only has every other M, T, W, and Th, then he's NCP - and Sheldon doesn't apply, so the advice was correct - BF is going to lose if this comes to trial. (It is interesting to speculate on whether the court would extend this to NCPs if pushed. There are good arguments both ways, but unless OP wants to spend roughly a bazillion dollars taking this to the IN Supreme Court, it doesn't apply today).
I just wanted to clarify that 'family members' can also include people living in the same house as CP in IN.