[doc1019]

What's the difference between asking Mary to pray for you in time of need or any other friend or acquaintance?

The assumption that those, besides the Holy Trinity, now residing in Heaven can even hear our prayers.

[mnehring]

That is a fair assumption and one that does separate Protestants from Catholics. However, I think most will agree the OP takes it one step too far (and a false claim we see often) that Catholics consider Mary or the Saints a ‘replacement’ or equal to Christ.

[Last Dakotan]

The assumption that those, besides the Holy Trinity, now residing in Heaven can even hear our prayers.

I'm curious how you've got your knowledge of what is and isn't possible in heaven.