I loved my IL's dearly, they accepted me with open arms, and I always called them Mom & Pop
. Sadly they've been departed for years
. DH calls my mom ~ Mama, or by her first name.
When our 4 IL's joined our family we told them we'd leave it up to them what they felt comfortable calling us
. Honestly, we love our kids spouses like our own, so feels natural the two local SonILs call us Mom & Dad, the 3rd SIL is out of state and calls us M&D ocassionally, but usually by our first names
. Family get togethers it's always Mom & Dad N. (for our last name) to avoid confusion. Sadly, within last few yrs several of IL parents have passed.
DIL, who is like one of our daughters, and I gave each other nicknames when she joined our family ~ we refer to each other fondly as MIL in 'mill' and I call her DIL 'dill'...other wise it's 1st name basis
. Works great for us.
IMO, once you marry into a family ~ be it good, bad or ugly ~ hopefully you join forces and work together bonding to be a loving family
. In our world, no reason to be so formal or uptight
. IL's should simply discuss it openingly and do whatever they are comfortable with.