Q: and if so do u have any strategies
A: this might take patience. it is like a doctor's diagnosis, you are the doctor. and you need to figure out how to take care of this piece. this task can be confusing and requires patience, but it can be done. it's usually just a long game of "what do we know" and asking many questions and eventually you will figure out what the solution is. if you test things categorically you can eliminate things instantly and narrow it down pretty swiftly. there are many questions you could ask, but i will try to list some of the questions that i usually ask. 1. does it seem to want to stay in the same form (same chords, same form, etc. same thing) for the 'other section.' some songs absolutely need that, and some songs are absolutely allergic to it. just doing a simple test and listen to whether it makes you extremely happy or uncomfortable, should be pretty easy to answer that one. another thing you might look at is lyrical content. another important tip, i heard a rumor that dave grohl gave this advice once, and the advice is called "get to the chorus"... like don't waste any freakin time if you don't have to. here's an interesting thing to check for: could you actually start with the chorus. in some cases this is just right, in some cases it's all wrong. a simple test should prove that one way or the other. here's a neat trick, do a regular run-thru of the chorus and figure out what wants to go Next. if that works then you could get your 'other section' from there. then you would be on to a different question which is which goes first and how. another strategy which is similar to one of the ones i already said, remember that the point of this whole thing is the part that you know already. the part that exists (the chorus, in this case). so just focus on that. that's the point of this whole thing. so maybe even start bargaining for that to be really the only part of the song in the entire song. and then just see how wrong that is and make adjustments from there. here's another thing to check for, starting with the chorus and then do another chorus with different lyrics, etc. i'm sure you've heard a million songs that are like that.  that's often just the ticket if you have a strong chorus that seems to be the star of the show. those are just some things to check for, over all this is going to be a puzzle but if you are gentle with it the answer will arrive. if the part you already wrote is great then it is guaranteed that there is a solution. also i almost forgot to mention, if you come up with extraneous things that are good but don't fit, always log those (separately)