beautiful phrasing slur

[Némo]

Hello, here is a peace of the first Sonata for clarinet and piano of Brahms.

\version"2.4.2"
\include"english.ly"
\relative c'' {
\set Staff.TimeSignature = ##f
\time 3/4
\key bf \major
 c4.\( ( ef8) d4~( | d8 b) c4.( g8) \) bf2 r4 | af2 r4 | g4 \f r4 r4
}

As you can see in the png attached file, the phrasing slur collide with 
the other. I search the doc and mailing list but can't find the « 
beautiful » adjustment for slur.
What can I do ?

Thank's

Olivier.

--
Olivier <address@hidden>