Hi maingun

1) Wind & earth quake is an occasional load.
2) Stress for wind & earth quake to be considered as occasional stress.
3) Load case you mention above is used for restraint load checking not for stress checking -B31.3 ( expect appendix P 31.3) hence stress type mention as OCC or OPE will not make any difference as far as load is concern.
4) Load case that is used for stress checking should be specify clearly as SUS, OCC or EXP since allowable stress criteria is different for different cases.
5) Displacement should be enter all those cases you mention though displacement for sustain case & hydro case should be very minimum.
6) As Mr. Richard mention be very careful to break system like this. Because header displacement affect branch & same time branch also affect header so clear picture can not be drawn unless combined analysis is done. When branch size is very small compare to header system can be break like this considering concept “ Dog can shake tail , tail can not shake dog”


Regards
Habib