Can’t invite child sims to birthday parties

[laurenciaelyse]

No matter how high my sims relationship is with another child sim, I can’t invite said child to a birthday party unless they’re in my house hold. 
I wanna invite my kid’s friends over for her birthday party but since children can’t plan events, I was trying to have her mom invite over her friends instead. I cheated her moms friendship up and everything but she still can’t invite over children for birthday parties. 

[ValFreya13]

@laurenciaelyse What day of the week and time of day? If it is a week day from 8am-3pm, it's possible the children are at school, and therefore busy so won't show up as inviable guests.

You should also make sure the mom actually introduced herself to the sim children as well. The relationship bar doesn't matter. She has to actually KNOW them. The cheat might not have worked if she has not formally introduced herself.