For the grammanatics ;)

I'm fishing for an answer, and hope to get a few bites here

I have an advanced student who said that she feels that something I wrote needs a ’to’ immediately before the word ‘do’. I told her that I don’t know a grammar based explanation, but that I’d find out. I wonder if it’s correct to simply say this is a collocation, and thus it’s just the way we speak, and that it’s not about grammar.

So, I’m asking this group if anyone can offer a GRAMMAR based answer, and not just offer examples of what’s acceptable / unacceptable in common speech or grammatically right / grammatically wrong. There’s a LOT of English grammar (yes, my native language) that I don’t know, and my grammar books don’t have the answers.

The first phrase is from a sentence that I wrote for her, to which she said she felt there ought to be a ‘to’ before the ‘do’. The subsequent phrases are other ways that I pointed out to her are also correct, and that also feel right to me. I pointed out that none of them have ‘to’ before ‘do’.

- is an indirect way of suggesting that someone not do that
- is an indirect way to suggest that someone not do that
- is an indirect way of suggesting to not do that
- is an indirect way to suggest to not do that - I suggest you not do that. / I suggest that you not do that. - I recommend you not do that. / I recommend that you not do that. - I advise you to not do that.

Thanks very much, I appreciate your help