Even though you have all canon cameras, which help, you have a CMOS sensor and DSLR sensors, so it’s never going to match perfectly.
You should be able to match your two DSLR’s by using the same lenses, like 2 L-Series lenses then match your white balance the same as well as F stop, etc.
The XA10’s CMOS will interpret light differently, so even though you match the settings as close as possible, it will still look differently.
It helps to take a series of static shots in different lighting and do a practice shoot with all 3 cameras pointing at the same subject. Adjust your settings on all 3 camera to get close to what you want, then do the same by tweaking the adjustments, keeping a log of your settings. Then when you go to post, you can see which setting give you the best results, thus giving you a guideline for future shoots.
There isn’t one answer that you can get to solve color grading. It takes experience and time to really know what settings and adjustments will work best.
Brent Dunn
Owner / Director / Editor
DunnRight Films
DunnRight Video.com
Video Marketing Toolbox.net
Sony EX-1,
Canon 5D Mark II
Canon 7D
Mac Pro Tower, Quad Core,
with Final Cut Studio
HP i7 Quad laptop
Adobe CS-5 Production Suite