The employer withheld deferrals for a small handful of participants and failed to deposit them in 2019 when the employer had a Simple IRA for it's employees. The Simple IRA was terminated at the end of 2019. The employer began sponsoring a 401(k) plan in late 2020. The employer discovered the deferrals withheld for the Simple IRA were never deposited and wishes to correct the error.
What is the proper correction for deferrals withheld under a plan that has since been terminated? Can the deferrals withheld under the Simple IRA and their associated lost earnings be deposited to the 401(k) the employer now sponsors?
Sorry if this is a simple one. I searched a bit through questions and didn't find a similar problem addressed.