You really want to pair up machines that have similar out put pressures.
Think of them as competing water hoses, only the hose with the higher pressure is going to deliver the most to the torch face and the other pumps will just add a very small amount to the overall output.
There should be several threads of discussions about how to connect multiple machines but bare in mind that a 10 lpm tee'd with a 4lpm won't get you 14 lpm. I think it will be more like 11 or 12lpm.
So for the power used you are not getting a whole lot of extra umph to the torch.
If you can get a homefil unit to refill tanks you could fill tanks with the 10lpm while you torch with the 3 and the 4 lpm units tied together.
Then when you have a full ( or half full, see some of the discussions ) tank then you can rage with a tank on the torch and that is a whole 'nother form of lampworking.
At least I think that is how it all works. I have been wrong before and I guarantee I will be wrong again.
OH and welcome to the addiction!