Modifying an Existing Hard Disk
The difference between using a new hard disk and an existing one is that an existing one already has a file and operating system which are to be preserved and expanded with additional ones, which might cause some problems.
Exception: The existing file and operating systems (incl. all files) do not have to be preserved. In this case, the partitioning process is almost as simple and straightforward as for a new hard disk. Just remove all existing partitions and start over the same way as with a new hard disk.
If already existing file and operating systems are to be preserved, you have to decide how best to change the existing partitions since the space occupied by the old partitions is to be utilized for the new partitions in most cases. (A reduction of existing "FAT" file systems is possible with the hard disk partitioner PartitionStar.) If needed, delete a partition no longer required and create two new partitions instead or vice versa.
It is impossible to list all of the possibilities within the framework of this text. In many cases your creativity and skill is also a decisive factor. A program that can take care of all of these tasks in their entirety and without any problems does not exist and will most likely never exist either.
Indeed, there are programs with a range of functions for modifying an existing partition exceeding the functions offered by this program but these programs usually cost significantly more than our offered program or promise more than they can keep without threatening the stability and/or content of your existing partitions.
The worst case scenario is that even a small partitioner error at a critical location during the modification of an existing partition could potentially destroy the entire file system.
Always make sure you have backed up all of your critical data 100% before starting to modify an existing partition.
However, if you have made such a backup you can also just delete the entire hard disk including all of the partitions and create new partitions. This way you do not have to make any compromises due to existing circumstances. This solution is not really the fastest one but surely the most orderly.