Lengthening ties

[Andrew Bernard]

In the following situation, how can one lengthen the ties between the grace notes and the normal music?

\version "2.19.24"

\relative c'' {

  c

  \grace {

    <g ~ g' ~>8

  }

  <g g'>16 ees' aes,8 c4 c |

}

I was hoping they would be longer by default.

Andrew