My Sims family members keep disappearing on my family tree [ Edited ]

[chilovescats]

Product: The Sims 4
Platform:PC
Which language are you playing the game in? English
How often does the bug occur? Occasionally (10% - 49%)
What is your current game version number? Idk
What expansions, game packs, and stuff packs do you have installed? All of them except for my first pet stuff and spooky day stuff
Steps: How can we find the bug ourselves? It will occur for the grandparents generation of whatever household is still alive Where all of the grand parents siblings will disappear
What happens when the bug occurs? What happens is the Sims will all disappear from my family tree leaving only the direct descendent
What do you expect to see? I’m playing a legacy challenge I’m doing the not so very challenge and I like looking at the huge family tree and right now my family tree is disappearing and it’s upsetting me
Have you installed any customization with the game, e.g. Custom Content or Mods? Yes
Did this issue appear after a specific patch or change you made to your system? Neutral/Not Sure 

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The first generation that happened to the brother didn’t have any kids so I thought maybe that was one of the reasons that he disappeared but his sister had three children and all three of those children had kids two boys one girl I ended up playing the girl when she moved out and then moved her brothers to unplayed now they both had kids and my Sims visited them and they had a very close relationship and then one day both of the brothers and their kids and their wives I’ll just disappeared from my family tree just like their uncle did

[chilovescats]

I’m really concerned because I have two households that both have a lot of kids and I don’t want their aunts and uncles and their cousins to all disappear

[xochiquetzl_xkvn]

There's a maximum number of Sims in game options.  You probably want to make sure that it's set to a higher number.

[chilovescats]

@xochiquetzl_xkvn Ok I’ll try that thanks