There are no hard and fast rules regarding division of assets on divorce and this can be a particular concern where the formal divorce follows some years after the initial separation.
However, generally the court seeks to differentiate between ‘matrimonial’ and ‘non-matrimonial’ assets. 'Matrimonial' assets are obviously those that have accrued during the marriage, 'non matrimonial' are those which did not. ‘Post-separation’ assets (such as a house that you now buy with your new partner) are likely to be considered non-matrimonial assets.
In general, only matrimonial assets usually warrant an approximately equal split. But - to answer your question -there is no guarantee that ‘non-matrimonial’ assets will not be required to be shared by a court. The extent to which they accrued because of the marriage is very relevant. For this reason, a bonus received by a husband from his work is more likely to be required to be split with his wife if a court views that success in the job has been achieved with the help and support of the wife during the marriage. On the other hand, a large inheritance, which has no connection with the marriage, is less likely to be required to be shared.
However, the key question which decides most contentious cases is whether the needs of the parties can be met without sharing any assets that were acquired after the separation. The relevance of this will obviously depend on your financial means and the likely 'needs' of your ex-partners, but if a court decides that these cannot otherwise be met, even an asset acquired by one party after the separation may well be taken into account, regardless of their source or link to the marriage.
As the law relating to this area is so complex, if you have ongoing concerns, I would strongly recommend going to discuss your personal finances and circumstances with a local solicitor. They will be able to provide specific advice on how to most effectively safeguard your position. They may advise that you each enter into a Separation Agreement with your ex-partners. This is a written document in which you and your current partner each agree with your ex-partners how the finances are to be divided. Although this is not legally binding, such agreements - particularly when properly and formally prepared - are often given due consideration by a court on dividing any assets. (Practically speaking, however, I recognise that you may decide that one of both of your ex-partners are unlikely to co-operate with this.)
I hope that this helps and am sorry I cannot give a more definitive question. As I'm sure you appreciate, much of how these principles are applied depend upon the precise circumstances of the couple in question.