Is there any way to transform multiple domains with their individual hosting into a single hosting plan with the respective multiple domains; which will use the same bandwidth and space quota of a single hosting plan?
you need a reseller package. Lunarpages has good references but I have no personal experience with them.
it is possible to consolidate multiple domains onto a single hosting plan while still using the same bandwidth and space quota. This can be achieved through the use of virtual hosts or add-on domains. Virtual hosts allow you to host multiple domains on a single server by assigning each domain a separate directory within the server's file system. Add-on domains, on the other hand, allow you to host multiple domains under a single hosting account, sharing the same resources such as bandwidth and disk space. Both methods provide a way to efficiently manage multiple domains without the need for separate hosting plans.