First you need to find out which tribe your future wife to be is, then according to her customs you will give her family a few hundred dollars. The Family will usually invest this money in zebu which is like money in the bank here. My ex employee who is Malagasy and from another tribe just needed to give the family 5 beers and $4. He had a good job on a boat and the family was happy to have their daughter marry because she was old at the age of 16 so it was difficult to feed her and he had a good job.
I went on to a civil marriage about 13 years ago which I showed my passport and a document that I was never married. My soon to be Malagasy wife just needed her birth certificate and proof she was not married and then we were married in the town hall in a small village and we had several witnesses from the community, that you will need to pay. The ceremony was in Malagasy and the paper work is in Malagasy and later on I got the French version. I said my "I dos at the proper time so I passed into marriage Several years later we had a catholic wedding in our home with priest, choir, witnesses and large group of family and friends and our children. It was a traditional wedding style atmosphere.Â
About Visa- Back then I was able to take my 30 day visa at the time and transform it to a family visa after several 90 day extensions and then after jumping through many hoops at immigration including I had to have proof I was not in trouble with the police in my country. Also, I took a morality test, an ethics format with several questions at the police station.  Your first family visa will be for 1 year which will take about a year to complete before you will need to start the same process all over again for a 2 year visa. The rules will change from from government Administration to the next. Several years ago family visas were only issued if you started a business, no business no resident visa, then you are a tourist again.
