It doesnt work???!!

ay, have to rewrite my question.
I asked a similar question already, but it's still not clear to me.

I know the man who was/is waving at us. - I know the man waving at us.

Now, does this also work for present simple and past simple tense? Like:

She's the one who wants to buy a phone. She's the one wanting to buy a phone. ?

Oder: Was this the man who lived next to you. -Was this the man living next to you?

Same here: How do the step taken (that was taken) by leaders of Athens reflect a turn toward democracy?
Answer: By people not wanting (who didn't want) to be in debt and ......

Hope you see what my problem is.
Thanks
LS