Short answer. Generally yes, but there's an exception for voluminous inventories. Article 827 of the Civil Code requires an incorporated document to be signed by the testator and witnesses on each and every page, except in the case of voluminous books of account or inventories — so a genuinely long asset list may be exempt from page-by-page signing.
What the law says
It must be signed by the testator and the witnesses on each and every page, except in case of voluminous books of account or inventories.
Civil Code, Article 827 — Incorporation by Reference. Read the full provision →
What the law says
such document or paper shall not be considered a part of the will unless the following requisites are present
Civil Code, Article 827 — Incorporation by Reference. Read the full provision →
Signing on every page is the general rule
Article 827 sets four requisites for an incorporated document to be considered part of a will, and the fourth is that it must be signed by the testator and the witnesses on each and every page. As a general matter, a document incorporated by reference into the will — such as a list of assets — needs that signature on every single page to count as part of the will.
The exception for voluminous books of account or inventories
The same requisite immediately carves out an exception: except in case of voluminous books of account or inventories. If your father's asset list qualifies as a voluminous inventory, it may be exempt from the page-by-page signing requirement that would otherwise apply. The article does not, however, define exactly how long or extensive a list needs to be before it counts as voluminous for this purpose. Because the article draws no line, whether a list is voluminous is a practical judgment, and the safer course for a borderline list is to sign every page anyway.
The other requisites the list still has to meet
Even with the signing exception, the list still has to satisfy the article's other three requisites: it must have existed at the time the will was executed, the will must clearly describe and identify it, including stating the number of pages it has, and it must be identified by clear and satisfactory proof as the document the will actually refers to. Skipping the page-by-page signatures does not excuse the list from these other conditions.
What happens if the requisites aren't met
Article 827 states that a document failing to meet these requisites shall not be considered a part of the will. So even a voluminous inventory that is properly described, identified, and existing at execution still has to satisfy those other requisites to be treated as incorporated into the will — the signing exception addresses only the page-by-page signature requirement, not the rest of what Article 827 demands.