I woulke like to note that sometimes it still works. For example we often have our staff travelling like: separate ticket on Finnair intra-european sector, then separate ticket on SN Brussels intra-european+long haul sector. Finnair check-in is always happy to check you in for all 3 sectors including SN sectors, also baggage is checked through your final destination shown on second ticket. Probably this have something to do with close co-operation of AY and SN, but still nice.