Yes, I have had that awful experience of having to get rid of partitions and it is a headache. The advantage in this case is that the amount of data on the old computer's hard drive is a known quantity so I can make that partition to fit (The old computer has a small internal drive.) Then the rest is TM. BTW, I think I can make the partition that has their old computer's data 'read only' and then there won't be any problems with any files on that getting deleted by mistake.
