Need Custom Script to maintain text field properties AND give user Rich Text Formatting

Using Acrobat Pro I created a fillable PDF form for my clients who copy and paste a large amount of information. Because they are using Acrobat Reader, I have designated text field properties with desired font and size, multi-line, check spelling, etc...and enabled "rich text formatting" so that they can manipulate their "raw" text as needed to be bold, italic, underlined, etc. However, when my client attempts to copy/paste source text into the desired form field, the information is retaining "source" formatting rather than what is already designated in the field properties. (Even occurs when source text is .txt - raw 'unformatted text'.)

Yes, I get that this is relates to the designation of "Rich Text Formatting." Does anyone have a Custom Format Script to use to circumvent the issue?

Thanks in advance!