We didn’t use a writing program until 8th grade, at which point I ran my daughter through a quick program called hands on essays. Other than that, she continued written narrations.
We used a combination of Easy Grammar Plus and Step by Step grammar.
I am actually convinced that formal grammar is better held off until high school. My daughter now has the maturity and critical thinking skills to understand grammar so much better than she did in middle school. Learning a foreign language really helps with grammar comprehension and most students study a foreign language in high school. I think this is really helping to cement grammar concepts for my daughter.