Joint Pain Relief from A.Vogel is excellent to help reduce the inflammation in the joints.
There is no interactions between the Crestor and this supplement.
For the Diovan, they say Devil's Claw (the plant in the Joint Pain Relief) could theoretically cause the medication to be eliminated faster, which could technically cause an increased in blood pressure. This reaction has not been observed on humans using that combination.
They still recommend to be careful and go gradually while keeping a close eye on blood pressure.
She has to be careful with Stinging Nettle because it is a diuretic that can definitely cause a drop in blood pressure (has been observed in humans). All the rest of the remedies are safe for her.
Here is a text with more information on arthritis and things that can be done.