It’s personal choice but I think there is a HUGE difference if the child doesn’t have their other bio parent in their life, for whatever reason. I never knew my dad, always called my stepdad “dad” (lived with him from the age of 2 so didn’t know any different) and he wouldn’t have stopped people to tell them I wasn’t his.
The difference with Rachel is that the boys have a mother who is still alive and, by all accounts other than theirs, still interested in being their mum. They don’t call Rachel “mum” and the older girls don’t call Josh “dad”. Yet when people comment on Instagram referring to the boys as her children, she doesn’t correct them.
after posting I saw someone had named her
(mattress and veggie bake comes to mind again) 
the others are there but that bit is gone
