In 1990, Simon and Susan acquired realty for $1 million, with Simon furnishing $400,000 of the purchase price and Susan providing the balance. Title to the property is listed as "Simon and Susan, joint tenants with right of survivorship." In the current year, Susan died first when the realty was worth $4 million. How much is included in her gross estate under the following circumstances?

(I) Simon and Susan are brother and sister.

(II) Simon and Susan are husband and wife.