We've probably all been daughters-in-law and mostly are now mothers-in-law. Is it helpful to reflect on how we felt about our own M-i-Ls when we were the D-i-Ls? I was married abroad and didn't meet my I-Ls until we landed back in England. It didn't take me long to realise I had little in common with them, but it didn't matter as we were unlikely to live in the same area, and in the event, we didn't. We were quite far from my parents too. Many years later, I have come to realise that my MiL was probably a little afraid of me as I had a good education and years of interesting experiences before I married her son. She was firmly under the thumb of my F-i-L and, with hindsight, I feel quite sad for her.
I have always been friends with my sons' other halves. My DD-i-L I met when she and my DS were managing winter sports hotels in Switzerland and she gave me a great welcome. We did have a lot in common and, although she and my DS are now divorced, we are still good friends. During isolation, she ordered an afternoon tea and had it sent to me. My other DS and his partner have been together for 25 years but never married. She's very successful in her career and works hard but nevertheless always welcomes me wholeheartedly. We too have much in common, and frequently recommend books we have enjoyed.
If there is anything I have said about getting on with in-laws, I'd emphasise that finding common ground, be it, books, cinema, sports, travel, can be a great way to treat one another as friends and equals - never as rivals.