If the decedent is not due a refund, then you can e-file (or mail) the return without including or attaching a copy of the court certificate (or court order) appointing you as personal representative.
If the decedent is due a refund, then you can e-file the return and mail Form 1310 separately without including a copy of the court certificate (or court order) appointing you as personal representative. You can also print and mail the final return together with Form 1310 without attaching a copy of the court certificate (or court order) appointing you as personal representative.
Finally, if the decedent is due a refund, you can print and mail the final return together with a copy of the court certificate (or court order) appointing you as personal representative but without having to mail Form 1310.
Sign the return with your name as "personal representative."
See https://www.irs.gov/publications/p559#en_US_2019_publink1000201744
Be sure to include with your mailing, a copy of the paperwork that gives you the legal right to sign as their representative too.
If the decedent is not due a refund, then you can e-file (or mail) the return without including or attaching a copy of the court certificate (or court order) appointing you as personal representative.
If the decedent is due a refund, then you can e-file the return and mail Form 1310 separately without including a copy of the court certificate (or court order) appointing you as personal representative. You can also print and mail the final return together with Form 1310 without attaching a copy of the court certificate (or court order) appointing you as personal representative.
Finally, if the decedent is due a refund, you can print and mail the final return together with a copy of the court certificate (or court order) appointing you as personal representative but without having to mail Form 1310.