How to build an SQS structure

How to build an SQS structure in ICET, the structure I want to build is as follows, I want to fix the Ba atom so that the Ga and Ge atoms are randomly distributed, I think this should generate a variety of structures, I refer to the tutorial given on the official website(Special quasirandom structures — icet documentation), but I can’t implement my idea, I would be grateful if someone helped me。

If the clusters-space is built with different sublattices, then generate_sqs(cluster_space, ...) should obey the allowed occupations of the sublattices.