dvd dinky questions-formatting, #of movies or shows per dVD, etc

Am making headway, having tried MS Sshow3, seems OK to work, But why the
)#*OUOIE@)$)_! isnt the format identical to MM so one can EASILY jump one to
the other....
Anyhoo, I made a SShow with FOUR slides and transitions, managed to get it
burned to DVD and shown on my Gateway 42 Pplasma tv.
Enthused, went to past incomplete shows from WMM and was able, i think, to
get em converted and burned to dvd.
Now I M ready for the big un, the 95 slide with music and trans in WMM.
Apparently there is a menu window that allows U to burn to disc several
separate shows, ie show files saved to your disc in appropriate format.
So now I have 3 shows, two trials at like 6 min each, one at 25 min, and
Kong at whatever.
All seems to go well, until the end of the 3+ hr burning. On arriving home a
window said "your disc was not blank, do you want to reburn."
HUH?
The short shows burned, then I left. By this time I said )(*#!@$)( again
and deleted clean the dvd.
SO'
Are we able to burn separate shows over time until the DVD is filled?
And nothing said noted anywhere about preformatting the dvd....
My heirs may be stuck with all these photos yet??????????

Larry in Mich, simmering, smouldering,etc