[Therion] Help! Large chamber problem

Hi I am fairly new to Therion, i worked through all the tutorials i could find and i am now busy doing my first actual survey with therion. The cave i am surveying has a large main chamber, about 70m wide and 100m long. The disto cant reach the edges of the chamber from the centre of the chamber, so as a result i surveyed several loops inside this one chamber. although i enclosed all these loops in single cave wall, it appears as if therion still sees this as multiple passsages and calculates the length of the cave accordingly so how do i approach this large chamber problem from a therion perspective? thank you in advance. Regards Gerrie Pretorius South Africa