Shell Programming and Scripting

I am newbie in UNIX, so please excuse me for the stupid question.
Here is a problem:
I created ksh script where the part of the functionality include an opening of a second session with another shell process "runrep"(runrep is a custom reporting shell designed by Advent Geneva).
When I run my script as it is now, as soon as it rich the line where it suppose to load a second shell - it just stuck at this point. In the output window I can see a child shell prompt. Looks like the second thread is created and the original thread is just waiting for the the child thread to complete.
Here is my questions:
1) How can I prevent my script from opening a new thread, so it would re-use the current thread and would be able to interact with the new shell?
2) If second thread is necessarily, how can I do command exchange between two shell threads?

Thank you for your help.

If it is possible, please, put the part of your script where it stops, the messages you have. With this will be easier to help you!

Regards.

Here is where is stops:

Code:

#open runrep shell
runrep -u $RUNREP_USER -w $RUNREP_PWD -f empty.lst

After this line, I have runrep-specific command "run report". However, it is just stop, unable to move forward, and showing me a new shell prompt:
runrep>

Code:

#open runrep shell
${GVHOME}/bin/runrep -f empty.lst -u ${RUNREP_USER} -w ${RUNREP_PWD} <<EOF
    read ${RSL_NAME}
    runfile ${RSL_NAME} -p ${PORTFOLIO_NAME} -f ${FORMAT} -o ${OUT_FILENAME}
    quit
EOF