Vitamin C and BHA moisturizer

It should be fine. It usually is the case of increased irritation probability, so i would try to incorporate the vitamin c when you aren’t using the moisturizer, but the cream is pretty gentle and has very low concentration of acids, so i think it will be okay if you use them togheter.

Usually, we use vitamin C in a morning routine and aha/BHA during evening routine, it also depends on how strong the concentration of aha/BHA is. If you use AHA with concentration about 30% then I wouldn't use vitamin C since it might be too strong, but about 10%? If you don't use it in one routine then it should be okay, Vichy even has a product that mixes vitamin C and Glycolic Acid and the effect is really good - it's called Glyco-C but in some countries you can only find Peptide-C ampoules

Its totally fine if you have a strong skin barrier. Layering actives is fine, but if your skin reacts negatively, you can stop the usage

If your skin can take it, why not? I'd like to share though that if it were me - I will use the Vitamin C for my morning routine (with sunscreen of course), and the other one at night. Im still very careful with layering acids in one go, but thats just me. Just dont forget to add a lot of hydrating products in your routine too.

If your skin can tolerate it, then go for it. If you hesitate, I suggest taking a patch test first on a lower side of your jaw. I have rosacea and sensitive skin but I have no problem mixing my vit c with salicylic acid/retinol. Good luck!