How to create partition without reformating

I suggest you rethink your project. Rounding up a herd of unicorns might be easier to do than would be to find what you're looking for - that way lies disaster. Free utility or paid, partition creation is best, most reliably, most safely done on a clean, freshly formatted drive, and performing partition manipulation on a drive already populated with data you wish to keep frequently has unintended, unfortunate, majorly inconvenient consequences, again regardless the utility used. Some paid partitioning utilities are reasonably reliable, but even then dismaying surprises are not unknown.