The paper proposes, under the roof-concept of a method abbreviated PILaD, a combination of quantitative and qualitative procedures aiming to clarify the relationship of "closely related languages" (Voegelin and Harris 1951). The method is based on the functional-pragmatic theory of 'Communicative Appa-ratus', a cross-linguistically operating interactive structure, which is modified by Lingua Receptiva communication. The data consist of 4 Russian-Ukrainian, 4 Polish-Ukrainian and 4 Polish-Russian conversations which were recorded with a digital camera and transcribed in a HIAT transcription format under the multiparty data program EXMARaLDA. Cases of 'problematic understanding' defined in terms of problematic utterances are related to the total number of utterances in a discourse. The communicative success is compared across the three language constellations and refined down to every participant. Statistical analysis gives an overall picture of how receptive multilingualism works in the three language constellations. The findings reveal that receptive multilingual communication between Polish, Russian and Ukrainian interactants is generally successful, yet, not symmetric, but depends itself on the direction of intelligibility. A summary of the PILaD method and the data base are attached.