Complex sentence: The club has a small amount of active supporters, called "Mławska Wiara" who also support powerhouse Legia Warszawa and have good relations with fans of KS Łomianki, whilst have major rivalries with Wkra Żuromin and MKS Ciechanów.
Split into simpler sentences: The club has a small amount of active supporters, called "Mławska Wiara". The fans also support powerhouse Legia Warszawa and have good relations with fans of Ks Łomianki, whilst have major rivalries with Wkra Żuromin and MKS Ciechanów.