Somebody please help before I lose the plot completely!

I have music VT playing as a Video Input in vMix.

I need to play along to this (in time) and this live sound is being recorded with a mic going through Behringer UMC404HD.

I want to record the combined audio (in time) but there is a delay between the audio on the VT and the live mic feed going through the USB interface.

I'm not particularly surprised by that, but the audio delay function does not seem to delay the VT audio in respect of the mic audio: it just delays the VT audio in respect to the VT image.

How do I do what I need to do to line up the audio from VT and audio from live mic. It's only about 100ms out but is very noticeable!

Save routing both the VT audio and live mic audio through the USB interface, which I was trying NOT to have to do for other reasons I won't bore anyone with.

Thanks for any help anyone can give.

vMix Rocks! (but has been very frustrating today!)

Steve