You can add ports to a grouped block directly to the block or add them to the internal algo within the grouped block.
To add ports to a grouped block:
Right-click on the block and navigate to the type of connector and value type to pass through the port.
The new port is added to the grouped block.
Double-click the grouped block to open it and notice the new input block.
Connect the new input block to the desired port.
To add ports to a grouped block from within the block:
Double-click the group block to open it.
Anywhere on the ADL canvas (not on a block or edge), right-click to display the context menu; then select the type of connector and value type.
The new port is added to the canvas.
Connect the new port to a block, if desired.
Return to the parent algo to see the new port on the block.