GST on Rent with Jointly Owned Property

One Commercial Property jointly owned by husband and wife

Now Husband is registered under GST

While letting out the property, GST is applicable on whole rent or on Husband Portion

Further,

In above example, suppose Husband use 30% of area and remaining 70% of area given on rent.

Out of 70% area, if we pay gst on only remaining 20% of area and show 50% in wife..... would it will be ok?