Using net ties for star ground in Altium
To do this you create a component with two pads set the type to net tie


Make the paste mask and solder mask with negative widths

Connect the pads with a trace.

Here is a good reference for more tips for creating net ties:
Net ties in Altium and how to use them
You'll also need to create net tie footprints for each width you need, so every 10 mils is good up to 100 and then every 50 or so.