Funds can be imported from Your Cause automatically. Just goto the Funds page in RaiseDonors and click the button, "Import from Your Cause". You are also free to create funds directly in RaiseDonors - but doing so will require you to also create the fund in Your Cause.
If you delete or in-activate designations in Your Cause, you must also in-activate that fund in RaiseDonors. There is no integration from Your Cause to RaiseDonors - so taking actions inside of YourCause will not be pushed into RaiseDonors (however the opposite IS true, changes from RaiseDonors will be pushed into Your Cause). This is particularly important because if a designation has been in-activated in Your Cause, but that fund is still active in RaiseDonors, then any donation sent to Your Cause will fail in the integration.
Clicking the "Load Funds from Your Cause" button from the Funds page in RaiseDonors will sync all the designations from Your Cause into RaiseDonors and also list any funds that have been in-activated in Your Cause.
As long as the bolded line below is a match, a duplicate will not be created in RaiseDonors. Here is the mapping of how RaiseDonors imports designations from OLOD into RD.
Rd.Fund.Name = Olod.Designation.defaultDisplayValue (if that is empty, use: Olod.Designation.longDescription)