I would ask that they go to God in Prayer.
When we go out and do things and head back home, we typically pray together. So far, they've asked me to pray. So even though they tell me they have prayed to Mary, Luke, Mother Theresa, and a few others, If I asked them to pray for me, I would ask them to pray to Christ.
Yes you would. Because God the Father is the supreme ruler of Heaven and Earth. And yes, they should pray to God the Father, the Holy Spirit and Jesus. But you would feel comfortable asking a Christian friend to pray for you right? I've already stated multiple times that Jesus is Lord and saviour and that there is only one risen Christ.
God is a living God and the Kingdom of Heaven is an exciting and dynamic place that interacts with us here on earth. The Bible, old testament and new is littered with stories of interactions between heaven and earth - visions, visitations and acts performed by citizens from the realm of heaven.
And as Catholics we believe that God, the most holy and powerful creator and Heaven and Earth, praise be his name on high, is not bound by earthly concepts - such as time. We as humans experience time as past (which we remember) present - the forever now - and the future, which we look forward to with great hope for the return of Christ in all his glory. Again there is plenty of evidence for God not heaven not being bound by our concept of time. How else would the book of Revelations have been written? How would the prophets of old foreseen the arrival of Christ who would bring a new covenant? Just a couple of examples for you.
So.... by extension we believe that while we still wait here on earth for Judgement day, in heaven it has already happened.
If you've followed me this far down the Catholic rabbit hole and I haven't lost you, then the next part is everyone that has departed on this earth is alive there in heaven right now. And what do they all do? Sit their on fluffy clouds and play harps? Of course not, they work with God to bring glory to his name! And we believe that means that they can interact with us and pray for us, in heaven just as the bible describes.
Long story short, as Catholics we believe we can ask people to pray for us both here on earth and in heaven. And crucially, every single one of them answers to God the Father and nothing is done without his permission. Therefore when we 'pray' to a saint or Mary, we're asking them to pray with us and for us. Clearly one should not spend all day bothering saints, they should spend the majority of their time talking to the trinity.
To Catholic properly is to live in joy and awesome wonder of the most Holy Trinity, that heaven and earth are not that far apart and accept that miracles happen around us everyday.