afterthought logical connection

[Logical Language Group <lojbab>]

For all the niceties of Lojban logical connection, I came across something
we can't do (I don't think) tonight in conversation session.  The statement
was something like

...sampymau binxo ... [to which I wanted to add in afterthought 
... ja [plujymau binxo], so as to properly group the metaphor as
[sampymau binxo] ja [plujymau binxo]

Unfortunatley, it seems that once you have said "binxo", there is no
easy way to go back and strongly tie it to sampymau.  The closest I could 
come in afterthought was

sampymau [binxo ja plujymau] binxo
sampymau [binxo ja [plujymau bo binxo]

What I really wanted was to be able to say "ke'e" before the ja even though
I had not said "ke", and have it (presumably by default, since more complex 
sentences would be ambiguous), presume the "ke" at the beginning of the
tanru - this seems like it will happen often in list-like OR tanru
.  Alas, I suspect that wouldn;t be possible.  Anyone have any ideas, or is 
this one we are stuck with?

lojbab