Seeing as you have not had a reply yet, I thought that I would give an opinion. It is merely an opinion because I have not welded this myself.

From what I understand, this is a free machining grade of austenitic stainless steel. This means that it has S added. This is obviously bad news for welding.

All that I can suggest is that you use a filler that has a high level of Ferrite, to try and minimise the hot cracking problems. You may try using a 29-9 type of filler. (E312)

In addition, use low dilution welding techniques, which means that you must try and weld with low currents and low interpass temperatures.

Hope this helps

Regards
Niekie Jooste