I typically will do it with blocked obstructions. You’ll need to have 3 to 4 XS for each row of piers. 1 just upstream, 1 at U/S face (if square) with blocked obstruction on (or center of pier if circular) then a D/S face (if square) with blocked obstruction on and then 1 just downstream with no blocked obstruction.
What percentage of the flow area will be blocked by the house piers? Another option would be to handle it just as you would trees, vegetation or anything else that increases the energy losses. Increase the roughness ‘n’ for this particular overbank area. See the reference manual 3-17.