Hang on - we always attribute a miracle to the INTERCESSION of a particular Saint.
We NEVER say or believe that a Saint - or anyone - actually PERFORMS a miracle under their own steam, geddit? In other words, God (be it Jesus, the Father, the Spirit or any combination thereof) of course performs the miracle, as He performs all miracles. But He does so at the request/petition of the Saint. That’s what ALWAYS happens, even when St Peter raised Tabitha from the dead, it was ONLY done BY God at Peter’s request, and not through any power of Peter himself.
Again, at Cana Jesus performed a miracle at the request of Mary - at her intercession. That is exactly how every miracle happens, apart from those of Jesus Himself, of course, who being God need not ask anyone else for help (I don’t know where you get the idea that He had to ask the Father at Cana - He was God, of course He didn’t have to).
I mean it’s not like St Therese or John Paul 2 were physically present at the time their miracles occured, were they? The miracles occurred AFTER their death.
So how exactly do you think that they did anything other than petition God for a miracle which was duly delivered. We can declare them Saints because this granting of their prayer demonstrates God’s love of them and the fact that their prayers to Him are efficacious as the prayers of all righteous people are. And righteous + deceased = in heaven, no?.