You could perhaps try renaming them something like:-
And locating them in the same folder.
Then using IfoEdit (free) click on the Create IFOs & then slect the folder & the first in the sequence and then in the box below tick "Same as source".
That should then process them & create the necessary IFO & BUP files.
You could always then process this back thru' DVD SHrink to get 1GB sized VOBs if you wanted.