add audio from a file to an image sequence

I must say it would be very helpful indeed

Can't beleive it's not possible! I have to choose between treating as image sequence, OR stitching an audio with the first frame of the sequence. The 2 is not possible at once, nor can be the audio source added later. How how how it is not possible???

Its ridiculous that something so simple as this doesnt exist yet, and that I have to go through after effects still