What is the ruling on a husband having intercourse with his wife before giving her the dowry and holding the wedding ceremony due to expenditures on his father, and what should be done about brothers who refuse to contribute to these expenses?

We believe that you should meet with your siblings and explain to them the obligation of providing for needy parents, and that this obligation applies to all children without exception, according to each one's financial ability and capacity. Advise them against abandoning their duty. If your siblings abandon their duty, you are not permitted to abandon your duty towards your parents, just as you are not permitted to abandon the provision for your wife. Therefore, you must fulfill both rights and perform both duties to the best of your ability and with what Allah has bestowed upon you from His bounty.