it is possible that my sister buy a property with another swiss man

No. As far sa Philippine laws are concerned, she's still married to the first Swiss man 

Your inquiry presents complexities that necessitate a more detailed discussion for precise legal guidance. To better understand the specific circumstances of your sister's situation, we highly recommend reaching out to us by visiting our profile and sending us a message. We also advise that direct communication with your sister will be instrumental in offering her tailored advice on appropriate remedial actions and safeguards for her interests.

Based on the limited facts you had provided, any property that your sister would purchase shall be considered as part of her community/conjugal property with her Swiss husband.