Multiple lave mics?

*lav sorry... it's late

I am doing a video for my father-in-law to give his mother for her birthday. This is something simple basically getting video of them talking (kind of like an interview). Now what I am trying to figure out is, is it possible to plug in more than 1 lav mic into the 5D Mark III using some sort of splitter?

Not looking to go all out on something like a H1 since this is just a simple thing I am doing for family .

In theory it is possible and ideally you would want to split the splitter to have a dual left on one side and a dual right on the other. Most Y splitters are for headphones and the like so you have one stereo in and two stereo out. Beacause you are, in effect, going the other way, you don't want to load the mics dual stereos one on top of the other when you could have one each side.

The other issue you may well have is Lav mics often require "Phantom Power". I don't know that a 5D would drive such mics.

This isn't insurmountable as you can buy quite cheap in line Phantom Power units. I'd be inclined to get one for each of the Lavs so that you can keep both signals completely separate right up to the time you inject them into the camera.