Settlement PM WO in Maintenance Activity Types (within a WO type)

Dear PM master,

i have a new requirement here, facing the issue in settlement rule (limiting and defaulting the specific maint act type to settlement receiver)

I already set-up default settlement rule by Work Order type is a standard functionality, but my company implement new accounting standard, that a major repair overhaul and Turn around (major maintenance, with a huge cost), must be settle to a deferred cost (i.e. WBS).

In My company business configuration, Work Order Turn around and Overhaul covered by maintenance activity type, which are linked by same WO type (preventive maintenance):

WO type:

PM02 (preventive maintenance), consists:

Mtc. Act Type:

001 (Turn around)

002 (Overhaul)

003 (Time Based)

004 (condition based)

005 (Plant Stop)

Now i want to default the settlement rule, in that PM02 order type which is within maint act type '001' or '002' to WBS or other costing receiver. when others maintenance act type remain same (defaulted by configuration in settlement rule profile in WO type)...

I just guessing, there will be a customer or user exit playing role in my case, but which one and how, that what i must figured it out.

Please do me a favour.

thanks