Fear of losing family fortune

Our family is very well off and for generations have for the most part kept marriage inside a small group of families. It started as the family grew in importance and as matter of getting richer and or power. They married within a group of 6 families and overtime the number of families decreased due to things such as wars and pandemics. One branch was so affected by the Spanish flu they vanished. Younger males went off to war and didn't return, so marriages like a great/great uncle marrying a cousin, he was 19 and she 32 had 4 children and he died before her. He died in WW2, so over the years since the number of children decreased and in 2018, I turn 20 and was told I was to marry my cousin who was 17 at the time. A second cousin I was told and the only acceptable person for me to marry according to the family. No others in the group families were able to be married being too old and unable to have children. The crisis was helped along by previous family members becoming monks and nuns so no children from them. Other families in the group aged too much and either had no children of their own or for one reason or another the children had already passed away. I wasn't exactly keen on marrying at the time, I was off to university and had hopes of a bit sexual fun. Which being married wouldn't help I thought. Luckily my cousin was gorgeous and quite shy at first, but she soon outgrew it. I was told as the older members of the family pass away the family fortune would come to me and or my family. If I was to pass away earlier, then they did. I did as require, why not my bride was gorgeous and soon after the wedding was pregnant. Going to university I did as I had wanted except, I lived off campus with my wife. Which was great she had no intention of ever going to university and became my perfect wife and companion. Anywhere I needed to attend I turned up with a gorgeous woman on my arm. Since our marriage we had 2 children, and she is currently pregnant. The family fortune is currently spread between 16 people down from 30 in 2019. The Coronavirus took 11 and 3 passed from other ailments like cancer. Of the rest my wife and I are by far the youngest. The youngest of the rest is my mother-in-law at 56, I've had several affairs since my marriage. Mainly during the later stages of my wife's pregnancies. Just flings, nothing serious and I believe my wife is my soul mate as they say. Several of the oldest relatives aren't doing very well at the moment. But I hope they recover soon. I'm not in any great hurry to inherit everything, I'm quite well as it is and so I like attending family gatherings like Christmas.