Helping someone marry without binding him or waiting for a compensation

Q: I am a young man who desires to marry during this year's summer holiday; if Allah wills and grants me success to do so. However, there is an old agreement between the people of our tribe reading as follows: "All members of the tribe agree that when any one of the tribe's young men wants to marry, all those who have married before should pay a sum of five hundred riyal as to help therewith the young man who intends to marry. The latter, in turn, has to participate in the future with all the other married members of the tribe and pay the same sum for the first one who is to marry after him and so on." (Part No. 19; Page No. 51) Thus all members of the tribe continue to pay the concerned sum to all young men who belong to the same tribe and desire to marry. It may be worth mentioning that some of those who receive such help may be careless with regard to the performance of Salah (Prayer), may not perform Fajr (Dawn) Prayer in the Masjid (mosque), and may be committing non-Islamic practices such as Isbal (lowering their garments), cutting the beard, and smoking. Moreover, some of them may spend the concerned sum on hiring a big wedding hall and a female tambourine player for ladies who charges two thousand riyals for this. The foregoing results in committing some Munkars (things or acts which are unacceptable or disapproved of by Islamic law and Muslims of sound intellect) such as the entry of the groom along with his bride to the lady's place etc. My question is whether it is permissible for me to receive this sum to spend it on some of my marriage expenses which are legally permitted? It may be worth mentioning that if I take this sum from them, I will participate with them in the future according to the agreement on helping young men desiring to marry and some of them may commit impermissible things as mentioned above. On the other hand, what do I have to do so that such an agreement will continue and the tribe remains united? I am waiting to receive your Fatwa and guidance as soon as possible. May Allah grant you success and help you to always act righteously.