How to create a list

I am try to create family placement in revit project. I wrote a script but I strake in certain level. I am using the familyinstance.bypointand level node to place the family if I mentioned the level node for level it working fine but I want the offset of the linked ceiling element. If I try to give it means the script is not working.

It requires a level and you are feeding a string.

Take the lsit of families after you created them and set parameter value

thks for ur quick replay. I am not check that.