Adding a DP34 will be fine but remember that the receivers that are hooked up to the DP34 will only be getting 3 sat. locations where as the DPP 44 will be getting 4.
Also, remember that the DP34 does not work with DPP seperators so if you have any dual tuner receivers hook them up to the DPP44 and use a seperator instead of having to run two coax runs for the inputs.