ObjectTemplate.SetPcoId

MDT description

This property sets the order in which PlayerControlObjects are used. Normally the order is generated automatically by the order in which PlayerControlObjects are added to each other. However, you can modify that order with this property. For example, If you add more thas one PlayerControlObject to another PlayerControlObject, you can set which which of these is associated with the number on the keyboard. SetPcoId of 0 means the first spot in that object.
Source and more details