Hi Munz
The threshold for being awarded PIP is higher than DLA, but I can't tell you whether she would lose her disability benefit altogether if she applied. You say her condition has deteriorated and she has a new condition as well as being profoundly deaf, so I would hope not.
With PIP it is not so much the condition/s that they are interested in, but how they impact on a person's daily life and/or mobility. It is easy for two people to appear to have the same condition and one person to be awarded PIP and another to be refused it. Fibromyalgia is one of those conditions which is often not taken seriously by the DWP and it can affect people in many different ways. She can always try filling in the take the PIP test
benefitsandwork.co.uk/personal-independe...nt-pip/pip-self-test - or look through the PIP guide and see how she things she could score and then make up her mind.
benefitsandwork.co.uk/guides-for-claimants/pip BIS