Add additional table to existing chart

I have a chart using the REQUESTS table as its base. I simply use a bar chart to give me a count of tickets generated by month. This works as desired.

Now I want to add the surveys table to this chart to plot count of surveys received per month. My survey table is a custom one I import from SDP.

How can I add this table to the existing one and have a combo chart with the new requests as a bar and surveys as a line. I'll even accept 2 separate axis if necessary.

I know I can probably write a query in SDP and use that in new able and use that. But don't want to. Thoughts? possible?

Thanks

David