How is VaR calculated for a pension company?

A pension company has an asset side and a liability side, and some capital. The key equation is $A = L + C$ Let's say the company wants to compute a 10-year VaR of its capital C. Normally, this would be easy. We just simulate the assets forward in time, and simulate the liability forward in time, and compare. But, for a pension company, the assets are typically fund investments . The liability is typically a set of obligations, which can be represented as a bond . This means that as time goes by, the funds, which are managed by somebody else, will regularly rebalance, react to changing market conditions, buy new bonds and get rid of old ones, and so on, all to ensure that the risk profile is kept of a similar level. But as time goes by for the liability, it's risk profile changes drastically, as obligations are met and the duration profile goes down. Obviously new obligations will arise in the future, but we do not know what these "new obligations" are just yet, so we cannot model them. How does a pension company then compute its VaR? Does it assume that both the assets and liabilities are static buy-and-hold investments, over 10 years? Or does it simulate the assets as the fund investments that they are, while keeping its liability static? The former seems more comparable but not realistic since we do not hold the asset-side funds' underlying positions directly. The latter seems less comparable but is what would actually happen if the pension company just waited 10 years.