To add to what Mayank has said, if you import your AcroForm into Designer, you can do it either of two ways:
1) bring it in as artwork, where the appearance is preserved, and this will generate a special static interactive PDF form, where you can overlay field objects to the appearance of the form.
2) you can also important it and Designer will do a best effort starting point to generate your dynamic, or static Interactive PDF. there are no restrictions in this path on the types of objects you can place on the boilerplate.
Documentation on these methods can be found here: https://helpx.adobe.com/content/dam/help/en/experience-manager/6-4/forms/pdf/using-designer.pdf
KJ