non-defining relative clauses

[anussky]

Is it possible tu use "that" in non-defining relative clauses?? yes/no why??

Thanks a lot!

[David L.]

Why would you want to?

Brit. Eng.:
The simple answer is, yes, if you wish to use incorrect grammar.
The trouble is, the use of 'that' in a non-defining relative clause will stick out like a sore thumb - far more than using 'which' with a defining relative clause, because the use of 'which' instead of 'that' is a common mistake!