My friend always intended to take the fridge, and didn't list it on the included appliances,  but the contract has a stipulation that all appliances would stay (she didn't notice that).She offered the buyers a concession of the cost to replace the fridge,  but they want her to put the original fridge back.She is thinking of just putting the house back on market.  

In PA, Act 129 covers abandoned tenant property:http://dornish.net/pennsylvania-finally-passes-act-129-law-on-abandoned-tenant-propertyDid the writ provided to the sheriff / constable contain the specific language that Act 129 stipulates for handling the tenant's personal property left behind?

Only stipulation, you must live in the home as a primary residence for at least a year. 

Are there legal stipulations to that type of "structure"? 

A. was yes   but the answer was C. yes unless seller has stipulated that he/she did not want to hear any offers under X#.

.- Note: Due to Landbank stipulations, I must use this as my primary residence for a total of 3 years.- Potential rental charge $1,000/mo in November 2021Investment Property #2 - 2 bedroom , 1 bathroom.

The offer does not matter a whole lot until you have estoppels, T12, rent rolls whatever you stipulate in your LOI. 

If your lease stipulates the after-hours parties, you shall send a certified letter to the tenant pointing at the fact that he is breaking the lease

The agreement did not stipulate anything if a sale happened prior to being 50% partners.

Not three.And, unless there is specific wording within that contract that stipulates he/she cannot act legally to attempt to sell, rent, lease etc that property for which the contract was constructed, he or she is free to enter into any negotiations, offerings, transactions or selling, renting, leasing etc his right in that property BECAUSE he/she owns the rights to that property as stated in the contract the original owner agreed to and signed.