Do you want more then 10 sims in one house ?

Here's how :

If you have three sims registered to one house you can then have a maximum of 13 sims in the house at one time.

If you have four sims registered to a house you can then have a maximum of 14 sims in the house at one time

First send the registered sims to the park
Invite ten other sims over - it is always best to have the 10 invited sims doing something - watching a movie - baking - planting - whatever you like - because when the home owners are sent home - the non working sim will disappear from this house

When one of the fourteen sims has finished an action - if you catch them in time you can assign them another activity and they will stay - otherwise they will disappear or head back to their own house.

To get them back you will have to repeat the process.

In the picture.. All my sims in one house!