This is a surprise for me to see the names of Marcus Alder and his siblings.
My brother has the Family Bible of Alder family.It was brought to Arkansas in the early 1900s by William Randoff Alder (my Grandfather) from Shepherdstown , W Va..He was the grandson of Marcus (b) 1768.
I had sent the Bible records to NGS but they have gotten misplaced and I had contacted yesterday the Library and they asked me to send again . Then they will be where more people could see.
On 10/11/2002 I had seen your message and didn't have time to answer.
The Bible never mentioned where he and Bro and sisters were born Their births and names are all like you have. Marcus married Priscilla Swearingen in 1891 After her death in 1823 he married Mary Page.
Their children were Marcus George Washington (b) 1825
Thomas James (b)1828------Elizabeth Pricilla (b)1831.
Thomas James married Mary Jane Bowers-----Their children were William Randoff (b) 1857 and James Marcus (b)1854..