Connecting Different Apps to Each other

Alicia, 

I'm not sure if you are talking about template projects/app that you are trying to tie together or apps that you are creating from scratch. 

You can always use connected tables - https://helpv2.quickbase.com/hc/en-us/articles/4570308461716-Creating-connected-tables - to tie tables from different quickbase apps together. 

Depending on the level of integration you are looking for - you may want to look at a custom built app that has the key elements you need, but if you are going to try and integrate expenses with a different external system - like quickbooks, just for your own sanity, you probably want to use the focused-app approach and connected tables or if you data volume and comlexity is low cross-app relationships... as long as you aren't seeing thousands and thousands of transactions a day - you can probably get away with cross-app relationships. 

Best of luck - and I'm sure there are voices here more insightful than mine.