How can I combine nine holiday light cords into one?
My wife has a large holiday village also, these are fairly low wattage so combining them on a power strip is ok. 
The advantage that she likes is everything can be turned off with 1 switch she actually has 3 power strips connected to power all the buildings and street lights, I measured the current and with everything running it was drawing almost 8 amps. This is well below what the circuit and power strips are rated for, I am glad she finally ran out of room to set up any more.