(85)Under current rules, participating insurance and reinsurance undertakings are granted limited possibilities to use simplified calculations for the purpose of determining their group solvency when method 1, namely accounting consolidation-based method, is used. This generates a disproportionate burden, in particular when groups hold participations in related undertakings that are very small in size. Therefore, subject to prior supervisory approval, participating undertakings should be allowed to integrate related undertakings whose size is immaterial in their group solvency by using simplified approaches.