notify ESA and PIP of health issues as an update?

My understanding is that I would have to notify both ESA and PIP of health changes like improvements in capabilities, long hospital stays, severe deterioration or death. However, as his appointee, if there is no serious deterioration in capabilities, do I have to notify them he has had a stroke this summer?
There were side affects of the stroke and medication has increased but there are no new symptoms or drastic deterioration in health and capabilities.
Those with no DWP knowledge would say yes, notify them, but I feel both ESA and PIP would then take the opportunity to set reassessment interviews, follow their previous practise of lying on the medical assessment paperwork, cancel benefits and I would be fighting 2 appeals over Xmas as happened last year with PIP. This would all increase my husband’s risk of a further stroke as he has severe anxiety and depression, high blood pressure, prior brain trauma and physical disability. and gets very upset when feeling his health issues are not believed.
My feeling is that I only need to notify them of improvement in capabilities. Would you agree, or feel I should write saying he had a stroke?

Thank you Gordon, I am very grateful for the fast response and reassured my decision is correct as there is no additional deterioration and I also feel 2 medical assessment appointments would be the only DWP response. Much appreciated.