Fillet in grasshopper 0.5xxx

hi all

I am trying to fillet different curves together in GH. But the old grasshopper (0.5xxx) does not have a fillet command. I tried joing the two by creating an arc but when i join curves and bake them, it generates a funny interface. Please let me know if anybody has a way to fillet in the old version or a definition that does the same. The new version seems buggy and crashes in my comp everytime I use it. There is an image attached for your reference. My eventual aim is to be able to 3d print this form.