G'day Justdoit,
Without seeing the youngsters up close it's hard to say for sure what the problem might be & what can be done to fix it.
We've had 2 foals in previous seasons that weren't so straight when they were born or became that way soon afterwards.
One was an easy pick, it became bucked over at the knees because it had contracted tendons & a course of calcium blocker injections (which was just an old school antibiotic) set it straight in a short space of time.
The other as it turned out was slightly off square all over, kind of like a table in a Pub that no matter which way you turn it...it will still wobble. I didn't pick this one, my brother did. He's got a very good eye & is exceptionally good at picking foals that are not quite right in their lower limb alignment goes, me..I'm not so good with them when they're that young, better when they're older but by that time it's often too late to do anything.
That second foal that was off a bit all over straightened up after maybe 7-10-14 days of being boxed with the mare. By far and away the best initial treatement is to box them & restrict their movement. A great many lower limb issues will come right on their own within that space of time and at the outside 14 days or so. If they don't show improvement in that time then it's probably time to get hold of the Vet again and think about your next move.
It might also be of some comfort to know that the time frame that you have in order to surgically intervene (strips etc) is relatively quite wide...it's not huge of course but it's a lot longer than many might think. It surprised me initially because I thought it was all but an immediate thing. I'd have to check with our Vet but from memory I think it's around 2-3 months. First off I'd try 7-10-14 days in a box 24/7, don't let them out and many of them will very quickly straighten up.
I noticed significant improvement in one of ours after just 2-3 days. Hope that helps.