Musical notation question

[Ruud van Silfhout]

Hi,

I have a question regarding musical notation/engraving. I am currently
typesetting a piece of music which has two voices in ones staff. At the end
of the piece the first voice goes from a g1  to an e1 ~ e1 and the second
voice from an f1 to a g1 ~ g1 (I think, I do not have the music at hand at
the moment).
How do you indicate in such a case, which note belongs to which voice as
there is no clue for the singer what note belongs to what voice (no stems).
The only clue visible is that the tie is in the direction of the first
voice, but that doesn't look too well anyway, so I am inclined to change the
tie direction, as this looks much better

Thanks in advance!

Bye,
Ruud van Silfhout