Need Some Boiler and Flue Advise

I have an oil boiler and just picked up a Bodureus coal/wood boiler and want to plumb them in series or parallel.....i want to have the coal be the main source of heat but if I run out I want the oil to fire up and keep the heat going......somewhere I had seen a schematic of this type of set up but cant remember where, does anyone know where to find it?
Also, what do you do about the flue? my oil is a 6in and the coal looks like a 7in.....do you put a "T" in line and just run them together or does this take some more engineered set up?

Before you go hooking both flue pipes up with a tee you might want to research your local regulations but most places it is one appliance per chimney flue

It is against code to run a solid fuel appliance into the same flue as an oil or gas unit. The reason for this is because the draft control on the oil or gas unit will allow lots of air into the flue if there is a chimney fire; destroying the chimney and maybe burning down the home.

Do you intend to burn wood in the hand-fed boiler?

That sucks to hear........I was planning on burning coal, I want to run the old oil and the new coal in paralell and have the oil as a back up....but again I only have one chiminey

Power vent the oil burner. There are ways to do the two units into one flue. One is with a stack damper on the oil burner or plumbing the stacks properly and it can work. However, most places it would not be to code. Check that out first.

Well, I didn't say you couldn't do it...just that it was against code. Depends what you want to do and what you are comfortable with.

Power venting the oil unit is a safe/compliant solution.