hello, brown rice is a good start. just be careful that it's heaty, so you have to start giving your baby water.
you can try convincing ur mil that fish is good for development of the brain, so can add in fish. Either scrape off before cooking or blend everything after cooking, just before serving.
you can also try convincing her it's good to intro veg, otherwise the child may not like the taste of veg when he/she grows older. the more common veg to use is spinach, chinese spinach (hoi cai).
a blender will be very useful, easier to blend other than mashing with a spoon/fork. A handheld one is good enuff and is easier to wash up.
my mum doesn't believe in freezing food, so she cooks fresh for my bb everyday, using slow cooker. So there'll b 2 servings in there for lunch and dinner. Breakfast is usually cereal or Eu Yan Sang Si Shen Brown Rice.
Then slowly, u can also introduce more variety, noting the 3-day rule for each new food introduced. There are lotsa websites and info on those, u can check out. Briefly, the safe ones are potato, sweet potato, pumpkin.
There are lots more which I can't possibly lay out here. Have fun