Question

Also, had they of done research on wills and added fact based information, than this would have made a crucial impact.

Is the writing after "Also" a restritive or nonrestrictive phrase?

I think that what is after "also" is restrictive but what is after the comma is nonrestrictive. Am I right?

Answer 1

Restrictive: essential
non-restrictive: non-essential

The base material is "this would would have made a crucial impact", and the material before is essential (restrictive).

Answer 2

http://grammar.ccc.commnet.edu/grammar/clauses.htm

Answer 3

Here's a better way to write that sentence:

<i>Also, if they had done research on wills and added fact-based information, then this would have made a crucial impact.</i>

However, "this" doesn't seem to have any antecedent -- it's not clear in this particular sentence what "this" is.