I currently have 4 DirecTV HR21 DVR's and really like them. In the not too distant future, I may want to add a 5th and possibly a bit later a 6th DVR.

I've had DirecTV for about a year and a half. If I call them in a few months about adding a 5th DVR, will they welcome my call and offer a free upgrade of my installation, or am I looking at a do it yourself project? If so, how complicated is it to install a 5th then later a 6th DVR to an existing 4 DVR system.

All my current DVR's have 2 coax cables running to them.