Understanding Society User Support

Dear all, I am trying to examine the class association between parents and children in Understanding society data. However, as I prefer using the NS-SEC (the five-class version) as class measurement, the answers to the question regarding the father/mother's occupation when the respondents were aged 14 are coded as SOC2010, SOC2000, SOC1990.

The derivation of the NS-SEC from SOC, according to the NS-SEC manuals by Office for National Statistics, needs the information on size of organizations, employers/employees, supervisory status and the numbers of employees (if self-employed), but such information is not available, as far as I understood, for the questions regarding fathers' and mothers' occupational status.
Another way to derive the NS-SEC is to use the derivation NS-SEC based on SOC table provided by Office for National Statistics. But the tables use 4-digit codes and the SOC coded in Understanding Society questionnaire uses 3-digit.

I am writing to ask if there is any way that fathers/mothers' occupation can be re-coded using the NS-SEC (five-class version)?

Thank you in advance.

Kind regards,
Min