Hi @philippeb,

You can only create a single geometry in the GeometryReplacer. If you want the arc and line to be part of the same geometry, please wrap them in a <path>:

<?xml version="1.0" encoding="US_ASCII" standalone="no" ?>
<geometry>
<path>
    <arcBy3Points>
            <startCoord x="100" y="0"/><midCoord x="80" y="40"/><endCoord x="50" y="50"/>
    </arcBy3Points> 
    <line>
            <coord x="50" y="50"/><coord x="100" y="50"/>
    </line>
 </path>
</geometry>

If the two pieces do not join, you can wrap them in a <multicurve> instead

<?xml version="1.0" encoding="US_ASCII" standalone="no" ?>
<geometry>
<path>
    <arcBy3Points>
            <startCoord x="100" y="0"/><midCoord x="80" y="40"/><endCoord x="50" y="50"/>
    </arcBy3Points> 
    <line>
            <coord x="50" y="50"/><coord x="100" y="50"/>
    </line>
 </path>
</geometry>

it's working good thanks a lot!

Is there a documentation about those <path> <multicurve> functions? (And potentially more of them I suppose?)

We don't document the FME XML externally, since it can change without notice as we add more capabilities to FME. It's best used to store geometry, or extract info from, rather than create geometry. That said, you can figure out a lot from the XML tab in the Creator transformer, or by extracting FME XML in the GeometryExtractor.