From SAS v13.0 onwards, the combination of data from overlapping fields observed repeatedly by XMM-Newton is possible, either to obtain a larger signal to noise ratio for a given source or to check for variability.
The tasks xmmselect and especget have been adapted to work with several exposures at once, making the work to be performed in the case of overlapping fields easier. The equivalent multiexposure tasks area called multixmmselect and multiespecget. multixmmselect starts a graphical user interface which allows the user to work with several event files from different input exposures simultaneously. Since multixmmselect handles at the same time event files from EPIC MOS and pn, as opposed to the xmmselect task, it only includes a subset of filtering parameters. A key feature of multixmmselect is the ability to extract spectra by selecting a common extraction region to all the single exposures at once. This is done through multiespecget, a modified version of especget for single exposures. Even further, it is possible, by selecting the appropriate parameter in multiespecget, to get as a result of running this task, to obtain a combined spectra and matrices including all the individual exposures. This is done through the use of the task epicspeccombine.
All the described functionality can be accessed in a simple way from the multixmmselect graphical user interface. multixmmselect also offers the possibility to obtain single exposure light curves and combined images in one single easy step. A SAS thread (Overlapping EPIC data treatment) describes in detail how to perform the described analysis.