I used to add them to lentils in a stew like dish, mainly to get my ALA requirements. I read that Omega 3 fatty acids are not heat stable but I am not sure at what temperature they are broken down.
This has been answered on the Medical Science Exchange. In short: boiling/steaming is around 100 °C, simmering even lower. Boiling point of ALA is 230 °C, so it should not be boiled out. The other concern, oxidation, also only sets in at 120 °C. If you're not using a pressure cooker, you will not hit 120 °C and the ALA should be almost completely preserved, as far as the science goes.