Hello Siddhi,
There are two ways to approach this:
1: Combine background and primary data. If you know the elementary flows from transport and combustion of coal, you can add the elementary flows to the process, along with a process of extraction of those fuels. Adding the rest of the product system will then give you a more or less complete model.
2: Use solely background data. There are some issues with combining data from several sources. Most databases have a way to calculate energy from coal combustion, and emissions from transport. Unless you have very specific data on these two processes, or data of a very high quality from elsewhere, i would suggest not mixing data sources unless necessary.
Regarding the impact assessment, if youre using OpenLCA 2, you can create your own impact assessment method, and add the GWP, Ozone depletion, and photochemical smog impact categories from ReCiPe. Using this LCIA method you created will yield results only on these categories.
Best of luck