Conventionally, it is possible to manually add your library of blocks as a Sublibrary in the tree structure of Simulink Library Browser using a Subsystem Block as described in Create a Sublibrary. The steps are repeated here for convenience.
To include a library in another library as a Sublibrary:
|1.||Open the parent library.|
|2.||Add a Subsystem block to the parent library.|
|3.||Delete the subsystem's default input and output ports.|
|4.||Create a mask for the subsystem that displays text or an image that conveys the sublibrary's purpose.|
|6.||Save the parent library.|
The following picture shows an example of Parent library and Sublibrary relationship.