Use to .uir files

Hello community,
I have four panels on one .uir file and was adding more content, until CVI got out of memory. I searched for solutions and found that I may need to split my content on different .uir files. I did it, but the buttons, gauges, etc that I took away aren't recognized on my main code. I get the next error: use of undeclared identifier 

How do I call the new .uir file? 

Thanks in advance