Once you achieve CCSM you maintain only the higher level (the CCSE is no longer applicable) unless it also expires.
You should be fine if both ISA exams are completed after the CCSM was achieved.
From the FAQ:
• I have a valid CCSE, CCSM or CCSM Elite. Do I need to maintain the lower certification(s)?
o Your goal is to maintain your highest certification or progress to the next level. You are not required to recertify
on the lower certifications. You will only recertify on a lower certification if you allow your highest level of
certification to expire.
• When I reach the level of CCSM or CCSM Elite do any previous certifications get extended to match the CCSM or
CCSM Elite?
o No, each certification has its own validity period. All previously obtained certifications will not be extended.
Additionally, when the previous certifications expire, they will not affect the certifications that are valid.
CCSM R77/R80/ELITE