A Bounded Context is a self-sufficient module of the system.
While it may be possible, my imagination fails to provide me with a scenario which works from a DDD perspective, and isn't also a purposely flawed design with an obvious fix.
It is possible to compose several such modules to create a new module. Usually though this new module does not provide a bounded context that is the super-set of its modules though.
For clarity consider several libraries such as a container library, a streams library, and a mathematics library. Each are separate bounded-contexts in their own business domains.
- The container library is in the business of structuring elements and managing their life-cycles.
- The stream library is in the business of inter-process communication (be that sub-process as in pipe and filter architecture, inter-os process, inter-network process, or time delayed/extra-process via a file).
- The mathematics library is in the domain of a field (or several fields) of math such as trigonometry, tensors, sets, etc...
You would rarely see these modules (and domains) combined into their strict superset: container/stream/maths. You are more likely to see these composed as a Game, a music mixer, or a transaction settlement service. The bounded context of these compositions is vastly different.
Alternate Reading of the question
Can a domain entity exist in more than one bounded context?
Is that sharing a bounded context?
Some bounded contexts must communicate with each other. This alone means that they must share some common understanding of the domain. Hence there are two bounded contexts with two identical/similar/related representations of a domain entity.
In a technical sense this domain knowledge might be encapsulated by a library used by both bounded-contexts. This library however is not representative of a bounded-context. On its own it is not a self-sufficient module, because while it facilitates communication, and may contain common manipulations, it is unaware of how each bounded-context will arrange, interact, and react to the communications it represents.
Depends on what you mean by Tour?
Is a Tour a flight+hotel+local activity?
- Then which bounded-context is responsible for the local activities?
Is a Tour a synonym for a local activity?
- Then it probably is a separate bound-context in this model.
- who is responsible for managing the Flight+hotel+visa+tour booking as a whole?