How To Make Particular Fields Of One Record Equal The Value Of Another

I have created my first two tables ever.

The first is ClientList, which contains typical contact and biographical information (name, address, citizenship, etc), and unique ClientID# for each client. The primary key for this table is the default Autonumber ID that comes with each new table.

The second table is WillInfo, which contains information specific to drafting the client's Will (e.g., spouse name, spouse address, spouse citizenship, similar data on beneficiaries, similar data on executors, etc). The primary key for this table is ClientID#.

I then created a One-to-One relationship between ClientList and WillInfo, binding by Client ID. All this appears to work.

My question arises because I have two clients who are married to each other, which means much of the spouse info I require for the WillInfo table in respect of these particular clients is already accurately recorded as client info in the Clientlist table. So for these specific clients (but not generally!), I want the spouse information in the WillInfo table (e.g., SpouseAddress, SpouseCitizenship for ClientID# 12.001) to EQUAL specific values provided in the ClientInfo table (i.e., ClientAddress, ClientCitizenship for ClientID# 12.002).

I read and understand this is the best approach, following the principle that data should not be entered twice, so as to increase efficiency and avoid mistakes and future problems.

My question is: How do I do this? In Excel, if the client info I wanted to replicate was in cells B4-B9, I would enter =B4, or =B5, or =B6 and so on in the cells for spouse info. What is the equivalent expression for replicating specific client info from a different table.