How might some groups use the declaration of independence in the future to gain rights

Well, I would assume by referring to the fact that Jefferson stated that all men were created equal and that they were endowed by their creator with certain unalienable rights that among them are life, liberty, and property (changed to the "pursuit of happiness" by Jefferson for the D. of I.)

That would provide the basis for ANY group to seek their own rights since they consider themselves on equal footing with all other people.

I hope this helps!