Mail addressed to claimant not the appointee

Visit by local DWP who confirms person is made appointee for claimant coming up to 16th birthday.
Day after 16th birthday - letter sent by DWP addressed to claimant inviting them to make a DLA to PIP claim
Appointee contacts DWP to question whether the appointee could legally act for the claimant if the letter was not addressed to them. DWP say to wait as their records had probably not been updated due to the short time (9 days) between appointment of appointee and initial letter to claimant.
Appointee contacts local DWP person who again confirms appointment and states that the appointee can act as paperwork has gone off from local office to PIP DWP to confirm appointment.
2 weeks after first letter ,another letter sent by DWP addressed again to claimant reminding them to make a DLA to PIP claim.

Can an appointee legally act if the letter is not addressed to them but the claimant?
I think Appointee will have to make claim irrespective as time is nearly out.

I'm not sure of the legalities of this situation but I am sure of one thing - failing to initiate the PIP claim in the designated time-frame is likely to result in the DLA claim being closed.

Thanks - That's the route that the appointee will be taking now - still has time - but will point out the situation to DWP.
I have mobile no of local DWP who made the appointee and has said they will help if there is a problem. if only they were all like that!

The appointee status should start as soon as the DWP visiting officer agrees that someone is an appointee.
When the DWP visited my wife & myself we were given written confirmation of my appointee status by the visiting officer before he left.

Pip 1 Claim was initiated today but appointee still not on system (over a month later).
For info - DWP stated they could still accept claim. Appointee was told that claim can be still be made if you verbally say you are DWP approved appointee or intend to seek appointee status.
They have e-mailed the local DWP (name of home visitor given)office to enquire further.
DWP unsure of legallities regarding addressee named on letters.
Also told to fill in and sign PIP 2 irrespective of addressee name.
So make the claim by the date given irrespective of DWP administration.