Hi, I’m Ame.
The title basically says it all. It’s basically the same system that VOCALOID has with lyrics inputting. For those who have not used Vocaloid before, it goes like this:
If you type something like [あの] into one note, の will carry over to the next note. (for romaji, spacing it like [a no] would work the same way)
I’m sort of aware that “Insert Lyrics” existing but making a .svp would be a lot more easier for me if at least an option for this exists.
Thanks.
HI, Ame.
Welcome to the forum! 
I believe that the Vocaloid way of doing it may be encumbered by patents, which is probably why SynthV behaves differently from Vocaloid.
SynthV uses the + to indicate that that a syllable is taken from the prior note, while - indicates a note uses the vowel sound of the prior note (a melisma).
So you could write "nico" in one note, and “+” in the next, and the first note would get the syllable “ni”, and the second “co”.
On the other hand, if the note had the lyric “nico”, the next “-”, and the next “+”, the first note would get the syllable “ni”, the second a continuation of the “I” vowel sound, and the third syllable “co”.
Try turning on this option:
(Translate with translator)