If you want to create an amalgamation that phrases to some multiple of 8, the easiest thing to do is start by choreographing a combination in whatever way you like, and then adjusting it by toying with those figures which are more flexible.
For example, I'll take a typical combo:
Two walks, link to PP, closed promenade, corte to DC, open reverse with closed finish, link to PP, open promenade, brush tap.
This combo is 5 eights + 6 beats. It might be nice to extend it two more beats, so that it's a clean 6 eights, and so that the brush tap becomes the final statement, or "cadence" to the 6th eight.
Two beats are easy to find, although less so if you want to stay strictly in syllabus. A link, of course, is two beats. But we're pretty swamped on links already. Another way to do it is to remove two beats somewhere, and add four somewhere else (or remove 6, then add 4, etc). That's what I think I'll do here:
I'm going to exchange the Open Promenade (6 beats) for a Promenade Link (4 beats). Now I need four more beats. I can add two walks in between the closed finish of the open reverse and the second link to PP. That would make the combo:
Two walks, link to PP, closed promenade, corte, open reverse w/ closed finish, two walks, link to PP, promenade link, brush tap.
That's a perfect 6 eights. But now after looking at it, here's something I like even better:
Going back to the original combo, I'd like to insert a back rock in between 1-3 of the open reverse and the closed finish. That would be 4 more beats, except that you can't do a RF back rock by itself and follow with a closed finish... you have the wrong foot free. So you have to exchange the closed finish with a back corte, which is essentially the same thing, but you're just adding a LF side & slightly back. So all in all, I've added 6 beats.
The reason I like this better is because even though I started the open reverse on count 3 (a little strange, but not bad), I've manipulated it so that at least the figure ends on phrase. In fact, with two walks, link to PP, closed promenade, corte to DC, 1-3 open reverse, back rock, and corte to end DW, we have a perfect four eigths... a nice, clean number for phrasing.
After that, I'll try to re-work whatever follows to make it phrase, also. But really all we have left is the link, open promenade, and brush tap. It's a pretty short phrase, so there's not much I can do with it unless I know what's coming next. The bigger point is that there are always a dozen ways you can work things to make them phrase, and even more if you stray from strict syllabus.
I hope that, by letting you into my thought process as I come up with this stuff, I've managed not only to give you a combo that phrases, but more importantly, given you some tools to solve these problems yourself. Even if I used a figure or two that you don't know (yet), you can use the same tools to amalgamate the ones that you do know, and create your own mini-phrases for dancing Tango.
Sincerely,
Jonathan