Double slur to specific notes of a chors

[Maik Schmidt]

Hi!

I've set three melodies for piano, working quite well. But now I've
come to a point where I do not know how to get it working.

I've got three chords, joint by slurs:

{\set doubleSlurs = ##t
<f a>( <f a>)( <f a f'>)}

Looks well except that in the original score the second upper slur
should not go up to the second F but to the A in the middle. Any 0 to get that?

Sincerely,
Maik Schmidt