multiple aspect ratios in same video/sequence

[Tim26322764ze30]

In case anyone has the patience for a newbie....

Trying to put 2 different aspect ratios in same video (maintaining ratios not converting).

16:9 (3840 x 2160) & anamorphic (4030 x 1704)(already desqueezed filmic pro).

I can get the correct ratios in separate sequences...

But when I combine (in main 16:9 sequence), anamorphic gets shortened in the width...

The work around I found was selecting the anamorphic clips and doing "Set to Frame Size."

Is this the correct way to do this or is there a better way? 

Really only concerned about quality loss.

Thank you!

[Ann Bens]

You will never get a perfect fit without scaling one or the other.

Set to frame size is a fast way of filling the frame.

I would set the timeline to 3840x2160.