You already mentioned that you had seen support for this in the Apocrypha (otherwise known as the Deuterocannonical text). As such, it became a Tradition to ask the Saints for intercessory prayers, because of the belief that they can in fact pray for us.
And on top of that...
my question is if there is biblical authority to support the proposition that when we are in heaven, in the presence of God, we can pray for the living.
In Luke 16 we read of the exchange between two men who had passed away:
There was a certain rich man, which was clothed in purple and fine linen, and fared sumptuously every day: And there was a certain beggar named Lazarus, which was laid at his gate, full of sores, And desiring to be fed with the crumbs which fell from the rich man's table: moreover the dogs came and licked his sores. And it came to pass, that the beggar died, and was carried by the angels into Abraham's bosom: the rich man also died, and was buried; And in hell he lift up his eyes, being in torments, and seeth Abraham afar off, and Lazarus in his bosom. And he cried and said, Father Abraham, have mercy on me, and send Lazarus, that he may dip the tip of his finger in water, and cool my tongue; for I am tormented in this flame. But Abraham said, Son, remember that thou in thy lifetime receivedst thy good things, and likewise Lazarus evil things: but now he is comforted, and thou art tormented. And beside all this, between us and you there is a great gulf fixed: so that they which would pass from hence to you cannot; neither can they pass to us, that would come from thence. Then he said, I pray thee therefore, father, that thou wouldest send him to my father's house: For I have five brethren; that he may testify unto them, lest they also come into this place of torment. Abraham saith unto him, They have Moses and the prophets; let them hear them. And he said, Nay, father Abraham: but if one went unto them from the dead, they will repent. [31] And he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead.
(Luke 16:19–31)
This is used as evidence of the ability to be aware of things going on elsewhere, and to communicate with people elsewhere (which would include doing so with God through prayer), even after going to "the place where the departed saints go".
