you can force a fare, either with a phase in **W1, or my forcing the fare base in the PQ by adding *Q in the WP format. Either way will remove the sabre guarantee on the fare...so there's that.

Most agencies are allowed to use guaranteed airfare waivers with the main 3 if either within 24 hours or 1 business day of the booking time, but they always require the original inventory to be in HK1 and not have had any changes done in *HIA. Depending on your agency's volume, it may have access to overbooking waivers, but again, would still require the class to match the fare base on the ETR