I found a workaround. With odoo studio I created an automated action with the following python code:

# Get the IDs of the existing stages you want to allocate

# Replace the IDs in this list with the actual IDs of your existing stages

existing_stage_ids = [113, 2, 123]  # Replace with actual stage IDs

# Check if these stages exist

existing_stages = env['project.task.type'].search([('id', 'in', existing_stage_ids)])

# Get the IDs of the stages that actually exist

valid_stage_ids = existing_stages.mapped('id')

if valid_stage_ids:

    # Update the project to link these stages

    record.write({

        'type_ids': [(6, 0, valid_stage_ids)]

    })

else:

    # Handle the case where none of the stages exist

    # You might want to log this or take other actions

    pass

Model: project
trigger: on creation