While an independent claim is always part of the common matter among its dependent claims, the opposite is not true: a claim dependent on several independent claims is never part of the common matter between these independent claims.
For example, an application contains three independent claims, A, B and C, and several claims combining the content of the latter, i.e. claims A+B, A+C, B+C and A+B+C.
Independently of the order and the manner in which the claims are presented, the application in question contains three sets of claims:
Unity or lack of unity is assessed firstly between the independent claims A, B and C: if these claims are not linked by a single general inventive concept, and they do not contain any same or corresponding special technical features, a lack of unity is present. The content of any of the dependent claims, e.g. of claim A+B+C has no bearing on this analysis.