Hi Pilou,

Would it be a suitable solution for you, though not very automatic, to :
1. First draw 2 straight lines, tangent to your circles (green in the example),
2. Bend those 2 lines according to the circles center line (without including the circles) (orange in the example).
3. Draw the largest circle tangent to the middle line so that it touches the end of the path.
4. Then draw the other circles tangent to the latest circle and the 2 bent lines.

I find it easier to fit the circles to the curved lines afterwards, like a blacksmith wrought ironwork.

Michel