Hi and welcome to Just Answer!
Because the estate is beneficiary of the 401k plan - you may not treat these funds as your own - and may not rollover to your retirement plan.
Funds should be distributed to the estate within five years - you may want to spread distribution over several years and minimize tax pressure.
Only if you are a beneficiary of the 401k plan you may treat it as your own.
I am surprise because usually the spouse is automatically treated as a beneficiary.
Since in your situation - the beneficiary is the estate - most likely you waived your rights.
Unfortunately - the brokerage company is correct for not letting the transfer to your own 401K plan.
However - you may rollover into so-called "inherited IRA" under the name of the estate - and as the executor of his estate - will be able to manage that account. Still full distribution is required within five years.
Let me know if you need any help.
Will I manage the fund and ask for x amount each year? Will this be taxable when I receive it? Would I be better off distributing to childrens trust - both adults and in a higher tax bracket than me or distribute it to me. This change was made (to have the trust as benificiary) per the attorney who made the will and after this one my husband had decided to leave his other IRA's to me which I have rolled over.