@Anonymous
The best way is to fix the constraints or delete them if you have a lot and not able to fix them easily after replacing, them, but I have another suggestion for you if that is helpful.
If you are thinking to replace components, I would suggest you another way if your parts are standard. Instead of using replacing, you can use the new functionality introduced in Inventor 2019 called Manage Components, in Manage components, there will be no same parts initially in your assembly and whenever the user selects a type for example a fitting here (e.g. 2") Inventor will automatically find 2" fitting from the path you specify, add it in assembly and Constrain it automatically. Now if you want to change 2" fitting with 3", when you select 3", Inventor will delete 2" fitting from the assembly, find 3" fitting, and also constrain it.
This is quite a handy and flexible tool, but you need to give a bit extra effort here to configure it, but this will eliminate the problems related to constraints and replacing components because you are not replacing any existing component but you are automating the operation of placing a component in Assembly and constraining it to the desired location.
See the below video, which describes it quite in detail.
https://www.youtube.com/watch?v=bsGK8uPAHnQ
Please also read out this document that describes how to use manage components in iLogic.
https://knowledge.autodesk.com/support/inventor/learn-explore/caas/CloudHelp/cloudhelp/2019/ENU/Inve...
If this is not sufficient and you struggle, please reach out to me with some test assembly attached here and I will try to help you.
If this answer has solved your problem please ACCEPT SOLUTION and hit like if you found it helpful..!
Regards,
Dutt Thakar
LinkedIn