The SEPP plan only applies to the account under which the plan was established. What to do in a different IRA account does not affect the SEPP plan.
You are not permitted to transfer or roll over any any amount to or from the account which is subject to the SEPP plan. Nothing other than the SEPP distributions are permitted to be taken from that account within the 5-year period beginning on date of the first SEPP distribution.
Without compensation from working, you are not permitted to make an IRA contribution. Distributions from an IRA or an employer's qualified retirement plan are not compensation. With regard to alimony, only alimony that is taxable to you is considered to be compensation. Regarding alimony, IRS Pub 590-A says:
For IRA purposes, compensation includes any taxable alimony and separate maintenance payments you receive under a decree of divorce or separate maintenance but only with respect to divorce or separation instruments executed on or before December 31, 2018, that have not been modified to exclude such amounts.
So it seems that your alimony will count as compensation.
