to increase vertical distance I mean.
Yes, you could get chain of the same size and tensile strength, split one link and weld it up again. BUT, It will NOT comply with local regulations in just about any country in the western world. If it breaks and kills someone the lawyers will have a picnic, you will probably go to jail , the authorities will sieze everything you own ,including your gold fillings and your dog will bite you. Your call.
If okorder /. This link would probably be a close match and pass through.
A small variation may not be a problem. For larger variations you should consider the weight of additional chain also. A freely suspended chain also causes tensile load at its top end due to its own load.
A GOOD WELDER COULD DO IT !!