Can crosspagepostback take a selected record id on a gridview and pass that value to the related foreign key field in detailsview in insert mode ?

you mean liek session or veiwstate or query string param? or what i dont really get your question any value you get from selected index you can grab on selcedindex event and then put it in session then onpostback do if(!ispostback)

{
}else

{

you go here! and then get it out of session and pass it to your details view? or am i way off
}