had been and have been

The person from I had been getting helpful advice whenever I needed it has migrated.

Wonder123had been and have been

The person who has been giving me helpful advice [until now] has moved.
(You are still getting advice at the time of the move.)

The person who had been giving me helpful advice [until some time ago] has moved.
(You stopped getting advice before the time of the move.)

CJ

Ok thanks, are my original sentences grammatically correct?

Wonder123Ok thanks, are my original sentences grammatically correct?

No. That's why I changed them.

CJ

Ok, What changes do I need to make to my original sentences to make them grammatically valid. Actually I want to keep the sentence structure/style as it is and still make it grammatically correct, is it possible.

Wonder123What changes do I need to make to my original sentences to make them grammatically valid

It seems to me that CJ has addressed this issue, Re-read his posts.

Along the advice given by others, this is my added two cents. If you insist on using this constructon and ask the volunteers to help you improve, bluntly, there isn't much we can impppprove based on the o.p. sentences. Like building a house, if the foundation and frame were out of plumb the rest of the structure will not be squared. I am sorry to tell you that this is the kind of phrasing I would

Yes I did, suppose if I would want to re-write the sentence of CJ in third person, how would the structure of the sentence be?

I yes agree with you, but I was trying to request CJ and see if CJ could rephrase my original sentences if and only if there is a possibility to rewrite those sentences.

I think "whom" comes in to picture especially when sentence written in third person, but not sure.

Thanks

It is pretty clear in CJ's last post. It is not correct, and that's why I commented " bluntly, there isn't much we can improve based on the o.p. sentences..."