can an appplicant make correction in requested "updated schedule1"

[zuma]

can an applicant make changes in the requested  updated schedule 1, background declaraton with no gaps in time and address ? we are expecting PPR  and completed all other requrements . few days back , the visa office asked for updated schedule-1 +PCC.my spouse missed 9 months of her personal history at the begining of her early 18. now the visa office asked an updated schedule 1, background declaraton .will it be a misrepresentation if she correct it in the updated form? should the principal applicant write it in the cover letter describing that she unwontedly and unintentionally missed it then and now included it?

thanks in advance