If others don't have the technical measures of "one heel makes up a stool and one backrest makes up a chair", then you can write it like this, but the scope is too wide and it is easy to be invalid. If others have it, you must describe your combination method in more detail, that is, write down your technical characteristics and the lower concept of "one heel makes a stool and one backrest makes a chair".
If you have the technical characteristics of "one heel forms a stool and one backrest forms a chair", that is, the patent right of the upper concept and the patent right of the lower concept, that is, the patent right of one or several connection modes, but others mention the connection modes that you didn't mention, it depends on whether the connection modes are mentioned or implied in your manual. It is generally necessary to judge whether such a problem is infringement through legal means. If mentioned, the odds may be even greater. Of course, it depends on the level of the agent and the judge's judgment.
Not detailed, for reference only! I also hope to discuss with you!