The only way to do that it to set up the field so it allows rich text formatting. The user can then manually set the vertical alignment by first showing the Properties toolbar (Ctrl+e), selecting the "More..." button, paragraph tab, and clicking the "Text Below" button in the vertical alignment section.
We put the form fields on in Adobe Acrobate Pro x, there are forms where we have two lines but if the field doesn't fill in we want it to align at the bottom. I've tried setting the field to multi line but it doesn't seem to show all the text if more than one line. The input of the field value is actually completed by using another application. Will setting the properties Option to "Scroll Long Text" allow for this to wrap and aling to the bottom? Or do we need to figure out something in the other application that is filling the forms in? Thanks