There might be a way to convert older FCD Virtual CD backup images (*fcd) to Virtual Hard Disk files (*.vhd) using IsoBuster. But most likely you will only be able to get the data out of FCD using the program.
Convert Virtual CD backup image to Virtual Hard Disk.
We found one software available in the database for this conversion.
Microsoft Windows software - convert fcd to vhd on Windows
A highly specialized and easy to use CD, DVD and blu-ray data recovery tool
Convert from fcd file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.