Ice,
You will need a combiner and several
modulators (not demodulators).
Basically, the modulator will take the signal from the UHF/VHF or A/V source and converts it to a channel between 2- 135.
Once converted, then you can connect it to one of the inputs on the combiner.
So if you want to create a mini home CATV network of 12 channels, you will need Qty 12x Modulators, and Qty 1x 12-way-Combiner