Missing PAYE records because person did not have NINO

Hello What is the best way to go about when someone came to the UK (legally, under EU rules), worked and paid taxes through PAYE and didn't get a NINO until recently (for various reasons)? They have P60 forms showing taxes paid, but nobody pushed them to get a NINO until recently, so those taxes are associated with a ghost. They want to get the taxes associated with their NINO now. P60 and P45 forms available for all the years.

Hi Radu,
If they were enrolled in a PAYE system, they might have been assigned a Temporary National Insurance Number (NINO).
If any of the payslips or P60s from that time do not display a NINO or show a different number than the one they currently have, it’s likely that they were issued a temporary number. 
If they are still employed by this company, they might be able to rectify this through their employers PAYE system.
If not, and they know their temporary NINO, they can reach out to PAYE Taxes at 0300 200 3300 to have the accounts merged. 
If they do not have their Temporary NINO, they can send their P60s and payslips to the Individual Caseworker at National Insurance as proof of their contributions, and they will update their records.
This evidence needs to be sent to the following:
Individual Caseworker
PT Operations North East England
HM Revenue & Customs
BX9 1AN 
A letter should be included with the evidence, detailing the reason for the submission.
It must also contain the account holder's full name, address, date of birth, NINO and be signed by the account holder.  
Thank you. 

Thank you. The problem was solved in a very straight forward manner via HMRC Online Chat. The agent was able to identify the records under a temporary NINO and associate them with the permanent NINO immediately. Now just waiting for the data to spread through the tax record (like NI contributions and income taxes paid). They'll go back to online chat if this seems to be taking too long.