Read the section on phase couplers. On the link I gave you .Your house is wired into 2 phases the x10 signal won't go from one to the other with out coupling them.
Using so many TM751 with Cm15 and only on 2 house codes will give you the biggiest headache. The TM751's will send a signal all at the same time and the Cm15 will also. SO this will flood your power line with PLC signals cause you automation not to work.
Start by getting a phase coupler. Many to choice from look here:
http://www.smarthome.com/_/ProductResults.aspx?Ntt=phase%20coupler Then remove all the TM751s and then try and see what happens.
If you are using remotes and have a big house try searching the forum for antenna mods to boost the range of the CM15a.
Those are starting points try it out then let us know....Will go from there.