"must necessarily include" is a correct and usable phrase in written English.
It is often used to convey a strong requirement or obligation. Example: In order to achieve a passing grade, your essay must necessarily include an introduction, body paragraphs, and a conclusion.
This exigency could be synthesized in a new design method, which must necessarily include the positive aspects of modular design.
The results allow the structuring of a proposal based on eight evaluation stations that must necessarily include the weighted cognitive and procedural aspects in a balanced way.
Without the prospect of an effective and cheap vaccine in the near future, any feasible public policy for controlling the dengue epidemics in tropical climates must necessarily include appropriate strategies for minimizing the mosquito population factor.
Interestingly, the leading steady-state physicist William McCrea was also a devout Christian who argued that cosmology, in whatever form, must necessarily include the postulation of a divine creator.
Since only 12 modules have been identified and each of the 9 pathways is split into 2 to 3 modules, some modules must necessarily include components belonging to more than one pathway.
In all likelihood, the physicians who participated in the survey were largely physicians with an interest in treatment decisions concerning "life-sustaining treatment"; thus, the sample analyzed must necessarily include substantial bias.
"Just as the right to free speech does not necessarily include the right to shout Fire!' in a crowded theatre, the principle of free markets does not necessarily mean that investors must be allowed to trample each other in a stampede".
"We have other options; they don't necessarily include Korea".
Intuition includes logic but logic doesn't necessarily include intuition.
The mission of the military doesn't necessarily include compassion.
However, the show wouldn't necessarily include those superheros.
