Is DS28EC20 (20Kb 1-Wire EEPROM) a secondary address of I2C?
As the protocol for DS2482-100 seems not to be register or memory address based but writing commands and reading data, I would not use the Mem functions. What you need to do is to command the DS2482-100 chip ovef I2C to do 1-Wire memory access, which sounds overly complicated as STM32 would be able to talk 1-Wire directly.