Challenging an early supersession of a pip award

My client was awarded - start date not known - standard DL and Mob PIP due to be reviewed March 2018. She was asked to complete a PIP review form - received by DWP Mar 2017 - and then attended medical assessment in June 2017. Scored nil points and decision dated 26/7/17 ended claim.

She has independently submitted an MR - no change - and referred appeal to Tribunals Service - and I have agreed to now represent. I have not had sight of decision 26/7/17 but have spoken to the DWP who have provided the info above.

I have written to the DWP to ask them to identify the ground for the supersession, the evidence used to make the decision and the effective date of the supersession decision to see if the supersession itself can be challenged.

Could anyone advise re the following?
1. My understanding is that the ground for supersession can be either an identified change of circs or medical evidence received from a healthcare professional.
In this case would the information provided by the claimant in the review pack provide the change of circs - I haven’t seen her review form and she cannot remember completing it but I suspect she stated that her condition had deteriorated - and/or would the subsequent medical evidence provided from the assessment meet the other possible ground for supersession. Or is it simply that the DWP must identify one or the other?

2. If either of the above could potentially apply how is the effective date of the supersession decided i.e. is it from date of decision - if medical evidence is the ground for supersession - or date of change of circs (or notification of change of circs) if the this is the identified ground.

3. Finally if the actual determination of the outcome of supersession requires the DM taking into account all the relevant evidence - what relevant evidence would it be reasonable to expect the DM to consider in addition to the assessment report?

And I assume it is worth challenging the supersession process as well as stating how the claimant meets the disability conditions but if the former is successful then the decison will not be valid and the original award will be reinstated?

Thanks very much

The UT judge’s decision CPIP/2621/2016 might be appropriate in this case.  The link:

https://www.gov.uk/administrative-appeals-tribunal-decisions/th-v-secretary-of-state-for-work-and-pensions-pip-2017-ukut-231-aac