thanks for the advise at the BOTTOM of this writing, but this was already done and indicated in my original problem description as below
" i did update the "project -> c/c++ build -> settings -> multicore -> multicore slaves" entry. "
as originally indicated, the following does no longer work after renaming both project files
" usual automatic procedure : after a "clean" command the core_0 master project builds followed by the core_1 slave project build.
same applies to debug, one core loads 1st, automatically followed by the other. "
what makes it fail is the following rename procedure indicated below
" now i rename the core0 and core1 projects.
i.e. adc_test_core0_m and adc_test_core1_s names being changed to
adc_usb_core0_m and adc_usb_core1_s within mcuxpresso. "
BOTTOM :
advise :
" 1) After change slave project name, please clean this project, then build again. "
" 2) In Master project, refer to below picture change to your new named .axf.o file "