yes that what i am thinking
sector 0 is erased
if the bytes to be changed are say bytes 5 - 10 for sector 15, page 1 then you

write changed data to sector 0/ page 1 / bytes 5-10
you copy bytes 0-4 of sector 15/page1 to sector 0/page1/ bytes 0-4 - for next loop 1
you copy bytes 11-255 of sector 15/page1 to sector 0/page1/ bytes 11-255 - for , next loop2
copy all other pages from sector 15 to sector 0 -

erase sector 15
copy sector 0 to 15 ( in

as you can see the smaller the sector erase the chip supports the better for small changes