Commitment and Undertaking left by my parents

My parents passed away and left us properties. The main house was titled to one of my siblings so as to avoid lien from the creditors. Before the title change, I had a house that I allowed my parents to sell and use funds so as to avoid forelosure of their dwellings due to their bank.They provided me with a "Commitment and Undertaking" which stated the amount of the loan granted to them, due date without interest if payment is done within the first 5 years. If paid at any time after 5 years ad 5% per annum interest will be reckoned from the day of receipt of grant until fully paid. There's also a statement in the commitment that "Being unpaid and outstanding, the herein creditor, shall have a lien over the said property and priority of payment, second only to taxes due the government and ahead of all others, in the event of sale, assignment or alienation of the property to a third person, for whatever reason and for value." "That we have personally committed ourselves including our heirs, assigns and successors-in-interest to faithfully and religiously comply, honor and acknowledge this undertaking." Last sentence stated" Jointly signed by us in the presence of our children who promise to honor all the ters stated hereto." The siblings and their spouses signed as witnesses on the agreement.

Now my question is, is there a way for me to enforce this agreement? The sibling that the house was titled, just for accomodation purposes, refuse to acknowledge the agreement and refuse to divide the property amongst the siblings. What do I need to do? Please help! I reside out of the Philippines and really need to know how to deal with this.

Hope to hear from you soon.