Problems with figured bass and alignment

[Raphaël ARNAULT]

Hello,

I work on lilypond to create a score of a baroque opera and I have some 
problems with alignment in the figured bass.

First, when I've a chord figured "#" and after another figured "7 #", 
and when I want tu use the bass figured extender, I don't managed to 
have the figured in the right order (the 7 above the extender).

I also want to have the solving aligned with the dissonance. Is it 
possible with Lilypond?

I joined you the two examples:

\version "2.12.1"
<< \new Staff {
\set Staff.instrumentName="[B.C.]"

\relative c {
\override Staff.TimeSignature #'style = #'numbered
\clef bass
\key bes \major
\time 3/4  d2. \bar "||" a2.

}}
\figures
{
<6 4>4 <_+> \bassFigureExtendersOn <7 _+> <6 4>4 <_3>2
}
>>

Thanks a lot;

Raphaël