Official policy to "blind eye" regarding counting child is up to 2 years old...we managed until Miss tb was a bit older (by being honest, and asking) with variable success: very good with AA, no luck with JL "try AA, they may let you in" -- which they did!, variable with CX. I think BA said OK until 3 (and in GC, not GF, which we didn't bother with).
My daughter is also 7 and (as detailed elsewhere) on recent trip, didn't bother trying for the three of us: just went in with her and I, leaving Mrs tb outside.
Not wishing for this to descend into the rights and wrongs of guesting an additional small child, just sharing real world experience.
Also don't want to debate too much about value of TP running just to get Gold (OWE) -- OP can decide value proposition for themselves, but on FT we do occasional have "folie a deux" about these things. I have occasionally timed a work trip (bring forward to December, or pushing back to Jan) to make OWE, but the dollar value of all the benefits of basic BAEC G in particular don't add up to more than a few hundred pounds for all but the most extreme user (Champagne guzzler crowd etc).
I'm EXP with AA, where the SWUs are much more valuable, but even then...
Once when I was BAEC Silver, and living in BOS, I contemplated spending $2k on a HNL TP run to make gold...my wife brought me flatly down to earth: asking how much free orange juice did I intend to imbibe over a year to justify the cost?!
Same here: OP could buy no end of F&M picnics for the cost of a substantial TP run, which would be far more pleasant than GF...
tb