OP, I want to defend you here as I truly believe you can live several people at a time and have no problem in theory with polyamory. That being said, I was also raised in part by a mother who believed in honesty. She told me about her depression and multiple suicide attempts when I was 8. I have been scared to death of her killing herself ever since. She told me various snippets of the hideous psychological abuse she was subjected to by my then alcoholic father when they were married when I was younger than that; I got the full gory details at 19, and ended up in counselling completely unable to reconcile my own experience of a loving father with the sadistic monster she described. She told me all these things very matter of factly, and probably thought she was just being honest. And as for sex positive... She was always very open with me about her bisexuality, her amusing anecdotes of her sexual history from the age of 14 onwards, and answered my every question about sex very frankly indeed. And, I suppose, "sex-positively". Hard to fault her for that in theory, but I feel I developed a pretty unhealthy interest in sex very early on, I used sexual language far too young, played rather inappropriate games at school with confused playmates, because of all this 'honesty' so early on when, as the classic movie would have it, I "couldn't handle he truth".
By and large, I do wish my parents (both of them, but particularly my mother) had worked s but harder to filter themselves and their truth from me, as the "honesty" my mother indulged in made me a much odder, outcast, sad and scared child who always felt terribly set apart from my peers. Children want to be normal, and they want to belong, and know where and how they belong, as a rule. They're very dull, conventional creatures by and large (at least once they're in school). I hope sometimes you'll think about that, and compromise your clearly dearly held principle of honesty on occasion in the cause of allowing them a childhood.
I am of course projecting. But it is another perspective. Honesty isn't necessarily all its cracked up to be when you're seven and are trying to make sense of a complicated world.