Don't try to amend the eviction complaint to add back rent. Sue separately in small claims court or start a new eviction case in July. Don't forget to add in the late fees! The small claims judge will not be happy to see a lawyer in court for non-payment of rent.
In order to appeal, she has to post a bond, & must pay all rent to the court pending the appeal. Make sure she has posted the bond. If she hasn't, file a motion to dismiss her appeal. You are entitled to receive the rent as she pays it. You may also be entitled to attorney fees. If you are entitled to attorney fees, go hire a lawyer. She'll end up paying for you. Eventually.
If she doesn't pay July rent on time, & doesn't pay it into the court, you can start a new ejectment proceeding. This time include all the back rent & late fees! If she wants to appeal, she has to pay the judgment to the court.
68 Pa.S. Section 250.513.
APPEAL BY TENANT TO COMMON PLEAS COURT
(a) Every tenant who files an appeal to a court of common pleas of a judgment of the lower court involving an action under this act for the recovery of possession of real property or for rent due shall deposit with the prothonotary a sum equal to the amount of rent due as determined by the lower court. This sum representing the rent due or in question shall be placed in a special escrow account by the prothonotary. The prothonotary shall only dispose of these funds by order of court.
(b) Within ten days after the rendition of judgment by a lower court arising out of residential lease or within thirty days after a judgment by a lower court arising out of a nonresidential lease or a residential lease involving a victim of domestic violence, either party may appeal to the court of common pleas, and the appeal by the tenant shall operate as a supersedeas only if the tenant pays in cash or bond the amount of any judgment rendered by the lower court or is a victim of domestic violence and pays in cash any rent which becomes due during the court of common pleas proceedings within ten days after the date each payment is due into an escrow account with the prothonotary or the supersedeas shall be summarily terminated.
(c) Upon application by the landlord, the court shall release appropriate sums from the escrow account on a continuing basis while the appeal is pending to compensate the landlord for the tenant's actual possession and use of the premises during the pendency of the appeal.
(d) Upon application by the tenant, the court shall release appropriate sums from the escrow account on a continuing basis while the appeal is pending to directly compensate those providers of habitable services which the landlord is required to provide under law or under the lease.
(e) As used in this section, the following words and phrases shall have the meanings given to them int his subsection:
"Lower court."
District justice, magistrate or any other court having jurisdiction over landlord and tenant matters, excluding a court of common pleas.
"Victim of domestic violence."
A person who has obtained a protection from abuse order against another individual or can provide other suitable evidence as the court shall direct.
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This is not legal advice and you are not my client. Double check everything with your own attorney and your state's laws.