Sorry if the title doesn't explain my question. I have a project coming up that will be using audio recorded in a studio at 24/48 and on a field recorder at 16/44.1 
The final project will be a DVD at 24/48 so I'm not sure what to do with material I record at 16/44.1 Will I have to recode that audio to 24/48 before I send it off to the editors?

No. They can import and convert the sample rate and export to another.

SONAR will convert the audio when importing, to the format used in the project.
Just export (if doing single tracks) to the format required in the other studio.
All the best.

Clips in a project may vary in bit depth, however; all the clips must be at the same sample rate. As mentioned above,  on import SONAR will convert clips to the project sample rate. Whether SONAR changes the bit depth depends on the "Import Bit Depth" setting in Preferences > File > Audio Data.

When this conversion from 44.1 to 48 happens, is it a small enough change that pitch shifting won't be an issue? Whenever I bring audio into Sonar I set up the project to match the source, so I'm not familiar with the side effects. 

The sample rate conversion has been an "under the hood" feature for a very long time. You have probably done it at some point and not realized (it doesn't pitch shift audio).

ampfixer
When this conversion from 44.1 to 48 happens, is it a small enough change that pitch shifting won't be an issue? 

Pitch shifting will not be a problem or cause any kind of significant alteration becauseof the sample rate conversion. Although most DAWs have caught up by now, SONAR has traditionally been very good at sample rate conversion. The concerns people had about sample rate conversion changing the sound dates back to the days when computers weren't powerful enough to take audio to the required level of precision.
 
Bottom line...you're good to go 

Thanks everyone, I appreciate the support.